A plane can fly 980 miles in the same time as it takes a car to go 420 miles. If the car travels 80 mph slower than the plane, find the speed of the plane.

Answer 1

p = plane speed
car speed = p-80
time = distance / speed
980 / p = 420 / (p-80)
(p-80)(980) = 420 p
980 p - 420 p = 80 * 980
560 p = 80 * 980
56 p = 80 * 98
28 p = 80 * 49
4 p = 80 * 7
p = 20 * 7 = 140 mph

Answer 2

980/280100