1 cuon day chia thanh 4 doan. Biet doan thu nhat =1/2 tong do dai 3 doan kia,doan thu hai =1/3 tong do dai 3 doan kia , doan thu ba = 1/4 tong do dai 3 doan kia ,doan thu bon la 19,5 m . Cuon day truoc khi chia dai bao nhieu met
ai lam nhanh, dung, co loi giai , minh t cho ok?