一又7/10×3.5-1.5÷2/7 99又18/19×38-3700 138/139×140怎么简算?一又7/1

问题描述:

一又7/10×3.5-1.5÷2/7 99又18/19×38-3700 138/139×140怎么简算?一又7/1

原式=17/10*7/2-3/2*7/2
=1.7*3.5-1.5*3.5
=3.5(1.7-1.5)
=3.5*0.2
=0.7
原式=99*38+18/19*38-3700
=100*38-38+36-3700
=3800-3700-38+36
=100-2=98
原式=138/139*(139+1)
=138+138/139