Chapter 7 - Algebraic Fractions - 7.4 - Addition and Subtraction of Algebraic Fractions and Simplifying Complex Fractions - Problem Set 7.4 - Page 300: 61

$\frac{m}{40}$

Assuming a constant velocity, she is completing 1/40 of the course every minute. Thus, multiplying by m minutes, she completes $m/40$ of the course in m minutes. We know that in fourty minutes, she will have completed the whole course, so it makes sense that when we plug in 40 for m, we get one.