1. The problem is to subtract 12 from 10, i.e., calculate $10 - 12$. 2. The subtraction formula is $a - b$, where $a=10$ and $b=12$. 3. Since $10$ is less than $12$, the result will be negative. 4. Calculate the difference: $$10 - 12 = - (12 - 10) = -2$$ 5. Therefore, the final answer is $-2$.