用简便方法计算。7y;I2w;Q/C5p8@)h:s-n+c7W)m.}(h0D
3＋3＋3＋3－47y;I2w;Q/C5p8@)h:s-n+c7W)m.}(h0D
算式：提示-s:F8h4S1K-c'l3g9b7y;I2w;Q/C5p8@)h:s-n+c7W)m.}(h0D
=*c4U:G-b*C8A)p/r+[2S8B,},_6g.@0N;~)A7y;I2w;Q/C5p8@)h:s-n+c7W)m.}(h0D