①170∶510
②1:
③ :
④0.8∶1.2
⑤3m∶18dm
⑥25∶75%
12÷0.9≈
12÷0.03=
25×40%=
2.4-2.4×0.5=
8×5÷8×5=
0.45:1.5
2.25: