Solve the distance, rate, time problem using a system of two linear equations in two variables. A plane can travel 960 miles in 2 hours (120 minutes) with a tailwind. The return trip against the wind takes 2 hours and 40 minutes (160 minutes). Find the speed of the plane in still air and the speed of the wind.

Define two variables (state what each variable represents).
Set up a system of two linear equations using the two variables defined in part (A).
Solve the system of equations by addition or substitution.
State your answer as a sentence and include units.