Problema Solution
A plane can fly 390 miles in the same time as it takes a car to go 120 miles. If the car travels 90 mph slower than the plane, find the speed of the plane.
Answer provided by our tutors
Let
v = the speed of the car, v>0
v + 90 = the speed of the plane
d1 = 120 mi the distance of the car
d2 = 390 mi the distance of the plane
Since speed = distance/time follows time = distance/speed
d1/v = d2/(v + 90)
120/v = 390/(v + 90)
........
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v = 40 mph
v + 90 = 40 + 90 = 130 mph
The speed of the plane is 130 mph.