Ok so 12 in. = 1ft 210 in = 17.5 ft 35 in = about 2.9 ft 17.5/2.9 = approximately 6 ft. I think the answer is 6 ft At the same time 210/35 = 6, which would make the length 6 in., because area equals base times height, so you just divide, which would make it 1/2ft. I would go with 6 in.