Solve an equation and list the steps Thank you

a+b+c+d=10 ⑴

2a+3d+9c+5d=55 ⑵

5a+7b+11c+9d=88 ⑶

2a+2b+2c+4d=28, b+7c+d=27

*2, get b+7c+3d=35, get 2d=8, d=4 substitution, get b+7c=23, b=23-7c- *5, get 2b+6c+4d=38,d=4,2b+6c=22 because b=23-7c substitution, get 46-14c+6c=22 8c=24 c=3

Substituting b = 23-7c yields b = 2

Substituting b, c, and d into the formula 1 gives a=1

So a=1, b=2, c=3, d=4

First subtract the formulas 2 and 4, eliminate a, and do the rest in turn.

1. a+b+c+d=10

2. 2a+3d+9c+5d=55

3. 5a+7b+11c+9d=88

4. 2a+2b+2c+4d=28

2+4__5___4a+5b+11c+9d=833-5___a+2b=5

2(a+b+c+d)=20

2a+2b+2c+4d=28

2d=8 d=4

a+b+c=6

It's a hassle to write, so I'll do it yourself! It shouldn't be difficult!

Solution: Let his heart beat x times before exercising. 55＋x＝130

55 x 55 130-55

x 75 A: His heart beats 75 times before exercising.

The equation is not very clear, the previous 18x-400 is in parentheses, that should be the numerator with -7x.

There are a total of x classes.

20x+130=25x

25x-20x=130

5x=130

There are 26 classes of x=26, and there are 25x=25 26=650 balloons.

There are a total of x classes.

20x+130=25x

25x-20x=130

5x=130

x=130÷5

x=26 There are 26 classes in total.

Balloons: 25 26 = 650 pcs.

Solution: There are x classes.

20x+130=25x

The solution is x=26

Then there are 26*25=650 balloons.

A: There are 26 classes with a total of 650 balloons.