Question

能简便的简便：13/8×25/4-3/8×25/4 （3/8+1/4)÷(1－2/5×3/4)

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解方程：
5/6x ×2/3=40 20%x ×3/2=90 7×1/7－6/7x=1/7

Answer 1

13/8×25/4-3/8×25/4
=25/4﹙13/8-3/8﹚
=25/4*5/4=125/16

（3/8+1/4)÷(1－2/5×3/4)
=5/8÷7/10
=25/28