Question 545499
An airplane flew for 4 hours with a 20-km/h tail wind. The return flight against the same wind took 5 hours. Find the speed of the plane in still air.
.
Let x = speed of plane in still air
then
from distance formula:
4(x+20) = 5(x-20)
4x+80 = 5x-100
80 = x-100
180 km/hr = x