Let m1 be the number of miles driven on the first day, m2 the number on the second day and m3 the number on the third day. Let h1, h2 and h3 be the number of hours driving on each of the three days. The piecewise function is composed of three parts: m1=60h1, m2=68h2 and m3=64h3. From this we can see the number of miles for each day, and the total number of miles is the three figures added together: 60h1+68h2+64h3.