A fence completely surrounds a pool, that is 30 feet by 10 feet. what is the approximate length, in feet, of the fence

Because the fence's dimensions is 30 feet by 10 feet, you can assume that one side of the pool is 30 feet while the other, non-congruent side, is 10 feet. The formula for perimeter, which you are trying to find, is 2L+2W=P. In this problem, 30 will be your L and 10 will be your W. Therefore, 2 (30) + 2 (10) = 80.

So 80 feet will be your answer.