Answer:
40 in
Step-by-step explanation:
For a width of w, the length is 3w and the area and perimeter are ...
A = LW = (3w)(w) = 3w^2
P = 2(L+W) = 2(3w +w) = 8w
We are given the area, so we can find w to be ...
75 in^2 = 3w^2
25 in^2 = w^2 . . . . . divide by 3
5 in = w . . . . . . . . . square root
Then the perimeter is ...
P = 8w = 8(5 in) = 40 in