1. **Problem a:** Find which operation to complete first in the expression $12 \times 2 + (6 \div 3)$. 2. According to the order of operations (PEMDAS/BODMAS), parentheses are done first. So, calculate $6 \div 3$ first. 3. **Problem b:** Find which operation to complete second in the expression $12 - 2 + 7$. 4. Operations of the same rank (subtraction and addition) are done left to right. So, first do $12 - 2$, then $+7$. The second operation is $+7$. 5. **Problem c:** Find which operation to complete first in the expression $10 \div 2 \times 5 + 7$. 6. Division and multiplication have the same priority and are done left to right. So, first do $10 \div 2$, then multiply by $5$. The first operation is $10 \div 2$.