Please help with this application question?

Question

A plane flew 600 miles with a 30 mph tailwind. On the return trip, the plane flew 600 miles into a 30 mph headwind. If the total flying time was 4.5 hours, how fast does the plane fly in still air?

Answer 1

Rate * Time = Distance

( V + 30 ) * T1 = 600
( V - 30 ) * T2 = 600
T1 + T2 = 4.5

Three equations, three unknowns...

T1 = 600 / ( V + 30 )
T2 = 600 / ( V - 30 )

600 / ( V + 30 ) + 600 / ( V - 30 ) = 4.5

Solve for V...