Students learn to solve wind and current word problems using a system of linear equations, as demonstrated in the following problem. Into a headwind, the plane flew 2000 miles in 5 hours. With a tailwind, the return trip took 4 hours. Find the speed of the plane in still air and the speed of the wind. The two variables used in this problem are p, the speed of the plane in still air, and w, the speed of the wind. So the speed of the plane with a tailwind can be represented as p + w, and the speed of the plane against a headwind can be represented as p - w. Note that this problem requires a chart to organize the information. The chart is based on the formula rate times time = distance. The chart is then used to set up the two equations.