20 practice questions for solving equations with answers 15

1.In a middle school, if the first year of Kifu junior high school students are asked to work alone, it will take hours to complete; If you ask the second-year students to do it alone, it will take 5 hours to complete. If you let the beginning.

1. How much time does it take for the second year students to work together for 1 hour, and then the second year students to complete the rest alone?

Students in the second year of junior high school also have to work x hours.

1/x=10/3

It takes 10 3 + 1 = 4 and 1 3 hours.

2.A rides from A to B, and B rides from B to A, both of them moving at a constant pace. The two men are known to have set off at the same time at 8 a.m., and by 10 a.m. they were 36 kilometres apart, and by 12 noon they were 36 kilometres apart. Seek ab two places away.

Let the ab distance be x, 12 o'clock - 10 o'clock = 2 hours, 10 o'clock - 8 o'clock = 2 hours.

2*[（36*2）/2]=x-36

The first 2 is from 8 a.m. to 10 a.m., for a total of 2 hours.

36*2 means that there are two times from 10 o'clock to 12 o'clock with a distance of 36 kilometers, that is, two people walk a total of 36 kilometers in two hours.

36*2) 2 Find out how many kilometers the two people walk in an hour, that is, the sum of the speed of the two people.

The equation is based on the phrase "I know that the two people set off at the same time at 8 a.m., and by 10 a.m., they were still 36 kilometers apart".

Results x=108

A: AB The two places are 108 kilometers apart.

3 A train from A to B, 90 kilometers per hour, delayed 12 minutes halfway, when the train sped up 10 kilometers per hour, just arrived at B on time, find the distance between A and B?

If the distance between stations A and B is S kilometers, then there are:

s/90=（s/2）/90+12/60+（s/2）/（90+10）

Solution: s = 360 (km).

A: The distance between A and B is 360 kilometers.

4 Xiao Ming went to his grandmother's house, if he traveled 5 kilometers per hour, he arrived at the scheduled time, he walked one-fifth of the way, and then took a car that traveled 40 kilometers per hour, so he arrived 1 hour and 24 minutes earlier than the scheduled time, asking Xiao Ming how many kilometers away from his grandmother's house.

If the distance between Xiao Ming and his grandmother's house is s kilometers, then there is:

s/5=（s/5）/5+（4s/5）/40+（1+24/60）

Solution: s = 10 (km).

A: The distance between Xiao Ming and his grandmother's house is 10 kilometers larger than the sedan front.

Solve equations. 1: 3／8 x－25%x=4 2: x÷4=30% 3: 3x+20%x=112 4: x-40%x=

Solution: 3 8 25% x=4 x=30% 4 3·2 x=112 60%x=3·6

1／8x =4 x= x=35 x=6

x=325: 14% 6: 75%x-25%x=16 7: x-20%x=44×50% 8: x-10%=18

14%x= 0. 8x=22 x=18

x=70 x=32 x= x=20

9 :60%x+25=40 10: 2x+30%x= 11: 1÷x=85% 12;40%x-5／12=3／4

x=1 solution : x=3 4+5 12

x=25 x=4 x=20／17 x=7/6÷2/5

x=35/12

13: 2 Jingyan x+7 14 15:160 25% 16: 3 8 x=4 15 4 9

Solution 2 slag manuscript oak x+7 = 2x= 3 8 x=3 5

x+7= 2x=9 x=3/8÷3/5

x= x= x=17 x=5/8

17: x÷2/7=7/3÷3/8 18: 3/4 x+1/2 x=45×1/3 19: 20:

x 2 7 = 56 9 2x = 1 5 x = 12 as shown next to 7

x=56/9×2/7 x=15÷ x= x=1/5÷12/7

x=16/9 x=12 x= x=7/60

Solve equation 1: 3 8 x 25%x=4 2: x 4=30% 3: 3x+20%x=112 4: x-40%x=

Solution: 3 8 25% x=4 Solution: x=30% 4 Solution: 3·2 x=112 Solution: 60%x=3·6

1／8x =4 x= x=35 x=6

x=325: 14% 6: 75%x-25%x=16 7: x-20%x=44×50% 8: x-10%=18

Solution: 14%x= Solution: Solution: 08x=22 solution: x=18

x=70 x=32 x= x=20

9 :60%x+25=40 10: 2x+30%x= 11: 1÷x=85% 12;40%x-5／12=3／4

Solution: Solution: Solution: x=1 Solution: x=3 4+5 12

x=25 x=4 x=20／17 x=7/6÷2/5

x=35/12

13: 2﹙x+7﹚ 14 15:160×25% 16: 3/8÷x=4/15÷4/9

Solution 2 x+7 = Solution: 2x= Solution: Solution: 3 8 x=3 5

x+7= 2x=9 x=3/8÷3/5

x= x= x=17 x=5/8

17: x÷2/7=7/3÷3/8 18: 3/4 x+1/2 x=45×1/3 19: 20:

Solution: x 2 7=56 9 Solution: Solution: 2x= Solution: 1 5 x=12 7

x=56/9×2/7 x=15÷ x= x=1/5÷12/7

x=16/9 x=12 x= x=7/60

1.｛5x+3y=348,3x+2y=216

Solution: System of equations 5x+3y=348 , 3x+2y=216 3=15x+9y=1044, 5=15x+10y=1080 - =y=36

Substituting y=3 into gives 5x+108=348

Get 5x=240

The solution of the original equation x=48 is x=48 and y=36

2. 7（2x+1）=49

Solution: 7(2x+1)=49 (both sides of the equation are divided by 7) 2x+1=7

2x=6x=33. （x+8）÷8=6

Solution: (x+8) 8=6 (both sides of the equation are multiplied by 8 at the same time) x+8=48

x=404. 4（x+3）=32×3

Solution: 4 (x+3) = 32 3

x+3=32×3/4

x+3=24

x=215. 3（x+5)-42=12

Solution: 3(x+5)-42=12

3（x+5)=54

x+5=18

x=136.（10x-90+2x）÷2=75

Solution: (10x-90+2x) 2=75 (both sides of the equation are multiplied by 2) 10x-90+2x=150

12x=240

x=207. （7x-3x+59）÷3=29

Solution: (7x-3x+59) 3=29 (both sides of the equation are multiplied by 3) 7x-3x+59=87

4x+59=87

4x=146

x=8. 9x-8=x

Solution: 9x-8=x

8x=8x=19. 12x+12=16x

Solution: 12x+12=16x

16x-12x=12

4x=12x=310. 144÷x+6=12

Solution: 144 x+6=12

144÷x=12-6

144÷x=6

6x=144

x=24