Answer:
-19
Step-by-step explanation:
1. multiply 9 and 30 to get 270
2. multiply 9 and a to get 9a
3. your equation would look like this 270+9a = 99
4. then subtract 270 from both sides to get -171
5. the equation looks like this 9a = -171
6. then divide 9 from both sides
7. the answer is a = -19
