Answer:
a = 8
Step-by-step explanation:
Step One - Add nine to both sides of the equation. This is the first step is to isolate the variable, a. This step will remove the negative nine from the equation.
3a - 9 = 15
3a - 9 + 9 = 15 + 9
3a = 24
Step 2 - Divide both sides of the equation by three. This is the last step to isolate the variable, a.
3a = 24
3a/3 = 24/3
a = 8
Since we have fully isolated the variable, a, we have determined its value.
Therefore, in the equation 3a - 9 = 15 the value of the variable is a = 8.