一堆沙子用去20%，还剩下1120吨，这堆沙子有多少吨？'z)s6v'R9V,Q-k
算式：提示6s(A2\5q:n4?4T3S1~-{7V*s'z)s6v'R9V,Q-k
答：这堆沙子有7x;g6P6V4i-d-W)?9Y吨。'z)s6v'R9V,Q-k