小梅投了4个沙袋，还有8个没投，她要投多少个沙袋？,o5P.X9l5s1Z-X3h0O
算式：提示:C0X1o5W7T4m3A5[0a;p(X;x8\)Q4`4C*c1}7s,o5P.X9l5s1Z-X3h0O
答：她要投.Q3d5G'S:[0b8O.c)~;c个沙袋。,o5P.X9l5s1Z-X3h0O