Picture a number line. the starting point is 0. go forward 5 which brings u to 5 on the number line. then since he lost 7 go back 7 which brings u to -2. now to get back to 0 you need to go forward 2. which means that he must gain 2 in order to get back to the starting point.
Sets of three integers that could be right triangles are called pythagorean triples. the only pythagorean triple including 7 is 7, 24, and 25. so the length of the other leg is 24 and the length of the hypotenuse is 25. hope this helped!
