Answer:
a= -5
Explanation:
To solve the equation, we want to find out what a is. In order to do this, we have to get a by itself. Perform the opposite of what is being done to the equation. Keep in mind, everything done to one side, has to be done to the other.
-3(9a+2)=129
-3 is being multiplied by 9a+2. The opposite of multiplication is division, so divide both sides by -3.
-3(9a+2)/-3=129/-3
9a+2=129/-3
9a+2=-43
2 is being added on to 9a. The opposite of addition is subtraction, so subtract 2 from both sides.
9a+2-2= -43-2
9a= -43-2
9a= -45
a is being multiplied by 9. The opposite of multiplication is division, so divide both sides by 9.
9a/9= -45/9
a= -45/9
a=-5