Question 118390
To solve this question you must first find a linear equation.

Let the speed of the slower train equal (x)
the faster train is 25mph faster than (x) so train 2=(X)+25

Because 4 hours elapsed we can state that (4)(X) distance has occured for the slower train and (4)(x+25) has occured for the faster train.

Because we are looking for the total distance between them we can add them to find the total distance.
train x+train Y= XY
(4x)+(4y)=456
because y (faster train) is represented by x+25. substitute the value.

your linear equation is below

4(X)+(4)(x+25)=456
expand the brackets and simplify the equation and solve
4x+4x+100=456
8x+100=456
8x=356
x=44.5

so the slower train is traveling at 44.5mph and the faster one is traveling at 69.5.

You can test this by substituting the numbers into your equation (4x)+(4y)=456
(4)(44.5)+(4)(69.5)=456.

Solved.