Question

A train leaves New York for Boston, 200 miles away, at 4:00 P.M. and averages 75 mph. Another train leaves Boston for New York on an adjacent set of tracks at 5:00 P.M. and averages 40 mph. At what time will the trains meet? (Round to the nearest minute.)

Answer 1

Step 1: draw a picture

Let's say they're running along the x-axis, so NY is at x=0 and Boston is at x=200mi.
Let's also say that t is the number of hours after 4pm.
Write an expression for the x-position of the NY train at time t. Write another expression for the x-position of the Boston train at time t. They will look like x=f(t). Use t=0 and t=1 (4pm and 5pm) to make sure your expressions are right. The question asks when they will meet, which means when will their x-positions be the same?