1. The problem is to simplify the expression $15 - 9$ and then subtract the result from 10. 2. First, calculate $15 - 9$ using subtraction: $$15 - 9 = 6$$ 3. Now subtract this result from 10: $$10 - 6 = 4$$ 4. Therefore, the final answer is $4$. This means if you start with 10 and subtract the difference between 15 and 9, you get 4.