The equation for the distance is:
(a/60) × 8 mi/min + (b/60) × 7.5 mi/min = D
We know that she runs 45 minutes each day, such that she runs at a rate of 8 miles per hour for a minutes, and then runs at 7.5 miles per hour for b minutes.
Now, remember the relation:
speed × time = distance.
Because a and b are in minutes, we need to rewrite the speed in minutes, remember that there are 60 minutes in one hour, then:
8 mi/h = (1/60) × 8mi/min
7.5 mi/h = (1/60) × 7.5 mi/min
Then the equation for the distance is:
a × (1/60) × 8 mi/min + b × (1/60) × 7.5 mi/min = D
(a/60) × 8 mi/min + (b/60) × 7.5 mi/min = D
Learn more information about speed here
brainly.com/question/4931057
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