Does anybody know the answer to this

Yes. this is easy. you know that the whole perimeter is 540. First you multiply the 150 by 2 because that is the length. Once you do that, you should have gotten 300. The next thing you do is subtract the length of 300 from the total perimeter of 540 because this will leave you with the length of the two widths put togather. Once you do that, your remaining peremeter is, or should be 240. The last step you bdo is take 240, which is the two widths put togather, and divide it by 2 to get each individual length. Once you divided, you should get your answer of 120. so the sides would be 150,120,150, 120 if you are going counterclockwise starting with the left side of the rectangle.