Math question im having trouble with

Question

Question

Train A and train B leave a central station at the same time. They travel the same speed, but in opposite directions, with train A heading towards station A, and train B heading towards station B. Train A reaches station A after 3 h. Train B reaches station B after 2 1/4 h. Station A and Station B are 420 mi apart.

What is the rate of the trains?

Answer 1

Answer : Rate of the trains = 80 mi/h

Workings

Assume rate of the trains is v

then total distance = 3v + 2 1/4 v = 420 mi

5 1/4 v = 420 mi

21v/4 = 420 mi

v = 80 mi / h

Answer 2