surround= 50 = 2(W)+2L>>>>>>>>>>( assume :the width is W , the length is L)
W= 2/3L>>>>>>>>>50 = 2(2/3L) +2L = 4L/3 + 2L = 4L/3 +6L/3 = 10L / 3
So>>>> 50 = 10L/3 >>>>>>L = 3*50/10= 150/10 = 15
So the length L = 15 m, >>>>>>>>>>> W 2/3 L =2/3 *15 = 10m
the width W = 10 m