Answer:

6 miles per 45 minutes

Step-by-step explanation:

1 mph  / 4 = .25 miles per 15 minutes

We can just multiply this formula by 8 since it is 8 mph

8 mph / 4 = 2 miles per 15 minutes

but the question asks for 45 minutes, not 15, so we can multiply our answer by 3 since 45 / 15 = 3 (15 x 3 = 45)

2 miles per 15  x  3  = 6 miles per 45 minutes

(or just find 3/4 of 8 since 45 is 3/4 of 60)