【12.9-（9.8-7.6）】*1.6
=[12.9-9.8+7.6]x1.6
=[3.1+7.6]x1.6
=10.7x1.6
=[10+0.7]x1.6
=10x1.6+0.7x1.6
=16+1.12
=17.12