Help me solve a math problem 15

60 Solution: Suppose there are x ducks in total According to the title:

x/2+x/4+15=x

Solution: x=60

Answer: (omitted) Let the total number be x and half, and make a fuss outside, then it is x 2, half of the half, and half of the cage is the total number divided by two, and then divided by two, yes x 4, and there are 15, then x 2 + x 4 + 15 is equal to the total number x.

And the one on the second floor won't just teach the bad boy Even the answer is wrong Dizzy.

Half is 1 2 of the total, half of the half is 1 4 of the total, and the remaining fifteen are 1-1 2-1 4 = 1 4 of the total, and then divide the fifteen by 1 4 to get the total.

15 (1-1 2-1 2*1 2)=60 (only).

You can have a total of x, half of which is x 2 and half of half is x 2*1 2

Since there are 15 left, so x 2+x 2*1 2=15 can get a total of 20.

The same backward method is easy to obtain.

The idea of elementary school, find the corresponding amount!!

The total - half = half, half of the half is 15, that half is 15 * 2 30, the total is 30 2 60

Half of the half, i.e. (1 2)*(1 2)=1 4, the rest is also 1 4 1-1 2-1 4=1 41 4 is 15.

A total of 15 (1 4)=60

Let the total number of ducks be x, and get:

1-1/2-1/4）x=15

1/4x=15

x=60

Relative velocity issues.

Set the speed of the fast train x

The speed of the slow train y is 184 + 168 = 352) 4 (x + y) = 352, regardless of whether it is in the same direction or in the same direction

16(x-y)=352

Solution.

x is the speed of the fast train, and y is the speed of the slow train.

x+y)*4=168+184;

x-y)*16=168+184;

x+y=88

x-y=22

The speed of the express train is v1=55m s

The speed of the slow train v2 = 33m s

First, find the common speed of the two cars, 168 + 184, divided by 4, equals 88In finding the difference velocity 168 + 184 divided by 16 equals 22, then the fast train is 22 meters per second, then the slow train is 33 meters per second, and the fast train is 55 meters per second.

Untie; Speed sum (168+184) 4=88

Let the speed of the fast train be x, and the slow train will be 88-x

16x-(88-x)*16=168+184x=55 slow train speed: 88-55=33

Let the speed of the fast train be x and the speed of the slow train be y

168 + 184 = 4 (x + y) = 16 (x - y) x = 55 m sec.

y=33 msec.

Solution: From the meaning of the question, it can be seen that the proportional function y=ax and the inversely proportional function y=6-a x intersect at a point.

So ax=6-a x

And because there is an intersection where the abscissa is 1

So substituting x=1 into the equation gives a=6-a a=3, so the system of columns and equations y=3x

y=6-3/x

The solution is x=1 y=3

So the coordinates of the intersection are (1,3).

When x=1, a=6-a

a=3, so its intersection point is (1,3).

Both the images of the proportional function and the inverse proportional function are symmetrical with respect to the origin, and according to the symmetry, their intersection is also symmetrical with respect to the origin, so the other intersection is (-1, -3).

Note: The analytic formula for the inverse proportional function should be: y=(6-a) x