An Air Force plane and a cargo plane left Tokyo at the same time. The planes flew in opposite directions. The cargo plane flew 112 km/h faster than the Air Force plane.

Question

After eight hours they were 4080 km apart. Find the Air Force plane's speed.

Answer 1

A=air force plan speed

C=cargo plane speed=A+112

8A + 8C=4080

Divide by 8

A+C=510

Substitute

A+(A+112)=510

Subtract 112 from each side

2A=398

A=194