Problema Solution
A cargo plane and an Air Force plane left New York at the same time. The planes left at the same time. The planes flew in opposite directions. The Air Force plane flew 90km/h faster than the cargo plane. After two hours they were 1380 km apart. Find the cargo plane's speed.
Answer provided by our tutors
let
x = be the speed of the cargo plane
y = be the speed of the Air Force plane
the Air Force plane flew 90km/h faster than the cargo plane
y = x + 90
after 2 hours they were 1380 km apart
since they are flying in opposite directions the sum of the distances of each plane equals 1380 km that is
2*x + 2*y = 1380
we are using the fact that distance = speed*time
by solving the system of equations
y = x + 90
2*x + 2*y = 1380
we find
x = 300 km/h
y = 390 km/h
the speed of the cargo plane is 300 km/h
the speed of the Air Force plane is 390 km/h.