Answer:
13
Step-by-step explanation:
Use the Pythagorean theorem:
Note: This also happens to be a Pythagorean triple where all three numbers are integers. These can be memorized.
48 mph
Step-by-step explanation: Add 42mph and 54 mph and you get 96. To find the average of the two --- divide 96 by 2 and you get 48mph as the average speed for the entire trip.
45 miles
first divide miles/minutes: 15 / 20 = 0.75
then multiply: 0.75 x 60 = 45
