Answer:
1. 18
2. 15
3. 10.5
4. 7.5
Explanation:
For 1, multiply 12 by 3 to get 36 then divide by 2 to get 18
For 2, multiply 10 by 3 to get 30 then divide by 2 to get 15
For 3, multiply 7 by 3 to get 21then divide by 2 to get 10.5
For 4, multiply 5 by 3 to get 15 then divide by 2 to get 7.5