1,解:原式=7.5x(1-0.9)=7.5x0.1=0.752,解:原式=0.65x(2.4-1.4)=0.65x1=0.653,解:原式=12.8+2.04x(10-0.5)=12.8+2.04x10-2.04x0.5=12.8+20.4-1.02=33.2-1.02=32.18
(1)乘号后面少数.应该7.5×?-7.5×0.9(2)原式=0.65×(2.4-1.4)=0.65×1=0.65(3)原式=12.8+19.38=32.18