Answer:
If Mary runs at 5mhp and Janet runs at 7mph, it will take them 45 minutes to reach a point where there is 1.5 miles between them.
Or, if you'd like a shorter answer:
45 minutes.
Explanation:
It will take both of them 1 hour to reach 2 miles between them. We are looking for 1.5 miles between them. So, split 1 hour into 4 equal parts.
1hr = 60 min.
4 x 15 = 60
Next, Add 3 of those 4 parts together or multiply one part by 3.
15 x 3 = 45
There's the answer.