1.4/5×2/7÷6/7×5/6
=4/5×2/7×7/6×5/6
=2/9 （约分整理可得,要细心）
2.1/7×5/12 +5/12÷7/5
= 1/7×5/12 +5/12×5/7
=5/12×（1/7 +5/7）
=5/12×6/7
=5/14
3.2/3+5/8 ×3/5 ÷9/8
=2/3 +3/8×8/9
=2/3+1/3
=1
4.[(3/5 -1/3)÷4/5]÷12.5%
=(3/5 -1/3)÷（4/5×12.5%）
=[(3/5 -1/3)÷1/10
=4/15×10
=8/3