Answer:
1. 12:15 try to round off, divide it into 3 = 4:5
2. 15:18 try to round off, divide it into 3 = 5:6
3. 40:15 try o round off, divide it into 5 = 9:3 divide again into 3 = 3:1
4. 12:100 try to round off, divide it into 4 = 3:25
5. 18:100 try to round off, divide it into 2 = 9:50
6. 12:18:100 try to round off, divide it into 2 = 6:9:50
