the way to solve this is by drawing a picture to get a visual on this problem. after that, you'll see that the 4 blocks north, the 3 blocks east, and the straight line across form a triangle. you can use the pythagorean theorem to find the third side.
a² + b² = c² ... use the two numbers given
(4)² + (3)² = c²
16 + 9 = c²
25 = c²
c = 5
the distance of the straight line between bob's house and his school is 5 blocks.
