108:0.72=10800:72=150:1
0.5：0.15=50:15=10:3
10/1:3/2=10/1×2/3=20/3=3:20
10/1:5/1=10/1×5=2/1=1:25/1:0.3呢？5/1:0.3=5/1×3/10=3/2=2:3