1.8/9×1/3+2/3
=8/27+18/27
=26/27
2.1除以（1/2+2/3)
=1÷1
=1
3.5.5除以（1-1/8-2/3)
=5.5÷(1/3-1/8)
=5.5÷(8/24-3/24)
=5.5÷5/24
=5.5×24/5
=1.1×24
=26.4
5/12×2/3除以5/24
=5/18×24/5
=24/18
=4/3
2/3除以（1/2-1/3）
=2/3÷1/6
=4