Need help please

Question

Jacob is 20 miles west of a meeting with Mark. Mark is 15 miles east of the meeting place. Jacob and Mark each leave at noon and arrive at the same time. If Jacob travels 40 miles per hour, how fast does Mark drive?

Answer 1

Let r = Mark's speed

d = rt

Jacob: 20 = 40t

20/40 = t

1/2 = t

Mark: 15 = rt

15/r = t

1/2 = 15/r

r = 30 mph