A plane can fly 560 miles in the same time as it takes a car to go 240 miles. If the car travels 80 mph slower than the plane, find the speed ( in mph) of the plane.
Let
x -----> speed of the car
y -----> speed of the plane
we have that
x=y-80 -----> equation 1
Remember that
the speed is equal to divide the distance by the time
speed=d/t
t=d/speed
car -------> t=d/x -----> t=240/x
plane ----> t=560/y
equate both times
240/x=560/y
substitute equation 1
240/(y-80)=560/y
solve for y
240y=560(y-80)
240y=560y-44,800
560y-240y=44,800
320y=44,800
y=140
x=140-80=60
therefore
speed of the car is 60 mph
speed of the plane is 80 mph