To find the perimeter, the equation is (w2 + l2 = p)
Where w is width and l is length and p is perimeter.
If you have the width, then you double it for both widths.
Then subtract that number from the perimeter.
150-60 = 90
90 is the remaining number for the lengths. Since both lengths needs to be equal, you split the 90. 45.
You length equals 45.
45(2) + 30(2) = Perimeter of 150.
Your answer is 45.