怎样简便怎样算:5分之1乘以8除以5分之4.5分之3加2分之1乘以5分之4.6分之5除以3分之2除以6分之5.

5分之1乘以8除以5分之4.
=8/5×5/4
=2
5分之3加2分之1乘以5分之4.
=3/5+2/5
=1
6分之5除以3分之2除以6分之5.
=5/6×3/2×6/5
=3/2
（8分之5加6分之5）乘以25分之4.
=5/8×4/25+5/6×4/25
=1/10+2/15
=3/30+4/30
=7/30
（6分之5减去3分之2）乘以10分之9.
=(5/6-4/6)×9/10
=1/6×9/10
=3/20
1减去9分之7除以8分之7.
=1-7/9×8/7
=1-8/9
=1/9