To prove two equations have infinite solutions, you have to prove that those two equations are the same equations, but in a different form.
For example: Prove the equations are infinite
5y=2x+7
10y=4x+14
If you multiply the first equation by 2, and substitiute any of the numbers, you will get 0=0
The best way to solve this is to make an algebraic expression to represent the situation~
If x is the speed of the first train and y is the speed of the second we can make 716.7 = x + y
the first train is 5.3 mph faster so x = y + 5.3
Now we can replace x with our new value to get 716.7 = y + (y+5.3)
Simplify and we get 716.7 = 2y + 5.3
Now all we got to do is simplify this equation, 716.7 - 5.3 = 711.4. Divide by 2 to get 355.7 for the speed of the second train. Since the first train is 5.3 mph faster, we add that to the second trains value and get our answer. The first train is going at 361.7, the second at 355.7
The percent change from 36 to 63 is 63/36=1.75 (multiply by 100 to get a percentage) 175%
The percent change from 63 to 36 is 36/63=0.571=57.1%