The first thing he has to do is take that "minus" sign through the parentheses containing the second polynomial. Some students find it helpful to put a " 1 " in front of the parentheses, to help them keep track of the minus sign. Here's what the subtraction looks like, when working horizontally.
The 7 miles and 24 miles make up two "legs" of a right triangle. The third side (or hypotenuse) is the distance between the towns. distance^2 = 7^2 + 24^2 distance^2 = 49 + 576 distance^2 = 625 distance = square root of 625 or 25
