0.76+（30-0.56）×1.6
=0.76+30×1.6-0.56 ×1.6
=0.76+48-（0.76-0.2）×1.6
=48-0.76×1.6+0.76+0.2×1.6
=48-0.76×（1.6-1）+0.32
=48.32-0.76×0.6
=48.32-0.456
=47.864