99.9*7+11.1*27
=11.1×9×7+11.1×27
=11.1×（63+27）
=11.1×90
=999
0.5/0.25+0.95/0.25
=2+3.8
=5.8
4.25/2.5*（10-0.1）+0.17
=1.7×9.9+0.17
=0.17×99+0.17
=0.17×（99+1）
=0.17×100
=17