3.4+3.4乘11+12乘6.6=3.4*（1+11）+12*6.6=3.4*12+12*6.6=12*（3.4+6.6）=12*10=1205.6乘0.375+八分之三乘5.4-0.375乘0.9=5.6*0.375+0.375*5.4-0.375*0.9=0.375*（5.6+5.4-0.9）=0.375*（10+0.1）=0.375*10+0.375*0....