Answer:
D. a=4
Explanation:
To solve for a, you isolate it on one side of the equation.
First thing you do is subtract by 15 from both sides.
Solve.
Add or subtract the numbers from left to right.
11-15=-4
-a=-4
Then, divide by -1 from both sides.
Solve.
Divide the numbers from left to right.
-4/-1=4
Therefore, the answer is d. 4.
I hope this helps, let me know if you have any questions.