3.6÷（1.2＋0.6）×0.5
=3.6÷1.8×0.5
=2×0.5
=1
1÷（2.1-2.05）×1.5
=1÷0.05×1.5
=20×1.5
=30
九分之五÷6＋九分之四×六分之一
=5/9×1/6+4/9×1/6
=1/6×(5/9+4/9)
=1/6×1
=1/6
（二分之一＋三分之二）÷（六分之五×五分之三）
=（1/2+1/3）÷1/2
=（1/2+1/3）×2
=1/2×2+1/3×2
=1+2/3
=1又2/3
二分之一×（七分之四－十四分之五）÷七分之六
=1/2×（8/14-5/14）×7/6
=1/2×3/14×7/6
=1/2×1/4
=1/8