I hope this picture helps you!
Step-by-step explanation:
Given c = longest of triange = 15m
Given b = short side of triangle = 9m
By pythagoras' Theorem,

56.25 minutes
Explanation: to find how long it takes to run one mile, divide 50 minutes by 8 miles.
50/8 = 6.25
Then you can multiply 6.25 by 9 to find the answer.
9 x 6.25 = 56.25 minutes