Since the shorter side has a length of 60 the other shorter side also has a length of 60 and the whole rectangle's perimeter is 400 if you add the shorter sides you get 120 to find the total length of the longer sides we have to subtract 400 by 120 and by doing that we get 280 so the total length of the longer sides is 280 and since there are 2 sides we have to divide 280 by 2 and we get 140 but, j *4 is 140 and we still have to find j so we divide 140 by 4 to get 35 and thus j=35
