Good evening Brian,
For this problem, let's look at what we're given. So we have a pool with a length that is 13 m (meters) longer than its width, and we're given the perimeter, or distance around the entire pool, which is 74 m.
We know that the pool has a rectangular shape and that the perimeter of a rectangle is width + length + width + length ⇒ 2(W) + 2(L).
Given the information provided, we can rewrite the equation to fit this problem. Since we're told that the length is equal to 13 m + the width, so we can represent the length as W +13 m. We can now rewrite the perimeter equation to be:
2(w) + 2 (w + 13 m) ⇒ 2(w) + 2(w) + 2(13 m) ⇒ 4(w) + 26 m = 74 m.
We're down to one variable now so this should be easy. Subtract 26 m from both sides,
4(w) = 48 m
Now divide each side by 4 in order to find the width.
w = 12 m
-Hope this helps!