1/4×2/3÷1/4×2/3
=1/4÷1/4×（2/3×2/3）
=1×4/9
=4/9
（3/5-1/4）×4/7÷1/5
=7/20×4/7÷1/5
=1/5÷1/5
=1
[1-(1/4+3/8)]÷1/4
=[1-5/8]÷1/4
=3/8÷1/4
=1.5
（2/5+1/3)÷4/5
=11/15÷4/5
=11/12
7/8×12/13+7/8÷13
=7/8×（12/13+1/13）
=7/8×1
=7/8
2/3+(4/5-3/2)×5/3
=2/3+4/5×5/3-3/2×5/3
=2/3+4/3-5/2
=3-5/2
=1/2
9/20÷[3/4×（2/5+1/3)]
=9/20÷[3/4×11/15]
=9/20÷11/20
=9/11