原式=1/5*(1/9+8/9)=1/5*1=1/5
1 / 5 ÷ 9 + 1 / 5 ÷ 9 / 8
= 1 / 5 ÷ 9 + 1 / 5 × 8 / 9
= 1 / 5 ÷ 9 + 1 / 5 ÷ 9 × 8
= 1 / 5 ÷ 9 × (8 + 1)
= 1 / 5 ÷ 9 × 9
= 1 / 5
解:
(1/5)÷9+(1/5)÷9/8
=(1/5)×(1/9)+(1/5)×(8/9)
=(1/5)×(1/9+8/9)
=(1/5)×1
=1/5
1/5÷9+1/5÷9/8
=1/5X1/9+1/5X8/9
=1/5X(1/9+8/9)
=1/5X1
=1/5
=1/5X1/9+1/5X8/9
=1/5X(1/9+8/9)
=1/5X1
=1/5
1/5*(1/9+8/9)=1/5*1=1/5