一批钢管叠成一堆,最下层有10根,每上1层少放1根,最上1层放了5根,这批钢管有多少根?(o+U4o7T/N5J0X
算式:提示(f*G:x.?)e,l3~9k3X(o+U4o7T/N5J0X
答:这批钢管有(O2B/G/a,l2^根。(o+U4o7T/N5J0X