First of all you need to work out 20 minutes in hours, this can be done by dividing 20 by 60:
20/60 = 1/3
Then you need to divide 15 by 1/3 to get the final speed:
15 / 1/3 = 45 miles per hour
He will need to be traveling at 45 miles per hour,
Hope this helps! :)
To make this a little easier, you would want to turn 3/4 into 9/12, to match 5/12's denominator.
You would then just add 7/1 to both fractions
(5/12+7/1=12/12 or 1 minutes)
(9/12+7/1=16/12=1 1/3)
So your answer would be 1.333... miles per minute
Hope this helps
5/8 * 125/125 = 625/1,000 = 0.625
62.5 percent
Solution: 62.5%