Expert: Chanda Walker - 11/17/2008

Question
The speed of train A is 20 miles slower than the speed of train B. Train A travels 190 miles in the same time it takes train B to travel 290 miles. Find the speed of each train.

Answer
Three equations, three unknowns.  There should be a solution.

First set up the equations.


Eq 1      A = B - 20

Eq 2      A * x = 190

Eq 3      B * x = 290


Then substitute Eq 1 into Eq 2 to generate Eq 4.

(B-20) * x = 190
Eq 4      Bx  - 20x = 190

now subtract Eq 4 from Eq 3 and solve for x.



20 x = 100

x = 5

Now put this back in Eq 2 and Eq 3 to find the speeds of A and B.

A = 38
B = 58

Does it also work in Eq 1?  Sure does!  Must be right.