distance rate and time

Question

Two trains leave the station at the same time, one heading east and the other west. The eastbound train travels 

12

 miles per hour slower than the westbound train. If the two trains are 

720

 miles apart after 

4

 hours, what is the rate of the eastbound train?

Answer 1

84 mph = the slower east bound train

96 mph = the faster west bound train

720 = 4(12+x +x) = 48+8x

8x = 672

x = 672/8 = 84 mph for the slower east bound train

x+12 = 96 mph for the faster west bound train

4(96+84) =4(180) = 720