7.2-7.2×0.9 =7.2×（1-0.9）=7.2×0.1=0.72
=7.2×（1-0.9）=7.2×0.1=0.72
7.2-7.2×0.9=7。2×（1-0.9）=7.2×0.1=0.72
=7.2✘(1-0.9)=0.72
希望对你有帮助……
