①18 × 3 =6 × 9
18:6=9:3
6:18=3:9
18:9=6:3
9:18=3:6
② 0.4 × 7.5 =2.5 × 1.2
0.4:2.5=1.2:7.5
2.5:0.4=7.5:1.2
0.4:1.2=2.5:7.5
1.2:0.4=7.5:2.5