Math word problem

Question

The perimeter of a triangle is 30 feet. The longest side is 1 foot longer than the medium side, and the shortest side is 7 feet shorter than the medium side. What is the length of the longest side?

Answer 1

Let L represent the longest side (in feet). The medium side is then  L - 1, which means the shortest side is (L - 1) - 7 = L - 8. Since the perimeter of the triangle is 30, L + (L - 1) + (L - 8) = 30. So 3L - 9 = 30. Adding 9 to both sides, 3L = 39. Dividing through by 3 yields L = 39/3 = 13 feet.