9/10-(1/4+7/20)/1/2X+3/5X=4.

问题描述:

9/10-(1/4+7/20)/1/2X+3/5X=4.

9/10-(3/5 )/1/2x+3/5x=4.4 9/10-3/10x+3/5x=4.4 9/10+3/10x=4.4 3/x=35 x=3/35