Problem
Yochanan walked from home to the bus stop at an average speed of \( 5 \mathrm{mph} \). He immediately got on his school bus and traveled at an average speed of 60 \( \mathrm{mph} \) until he got to school. The total distance from his home to school is 35 miles, and the entire trip took 1.5 hours. The following system of equations represents this: \[ \begin{array}{l} 5 x+60 y=35 \\ x+y=1.5 \end{array} \] Yochanan walked how many miles?
Solution
Step 1 ：Substitute the second equation into the first: 5(1.5-y)+60y=35
Step 2 ：Solve for y: 7.5 - 5y + 60y = 35
Step 3 ：Calculate x: x = 1.5 - y
