Answer:
a=11
Explanation:
So, the line that (9a+6) and 75 are sharing is straight, meaning that it is 180 degrees. Also, (9a+6) and 75 are sharing the line. Even though we don't know there exact measurements, when know that by adding them together we will get 180 degrees.
1. (9a+6) + 75 = 180
2. 9a + 81 = 180
3. 9a = 99
4. a = 11
Hope this helped!