Answer:
B. a = 5
Step-by-step explanation:
3(a - 4) + 1 = 9 - a
Distribute the 3 into the parenthesis.
3a - 12 + 1 = 9 - a
Add -12 and 1.
3a - 11 = 9 - a
Add a to both sides.
4a - 11 = 9
Add 11 to both sides.
4a = 20
Divide both sides by 4.
a = 5.
Proof:
3(a - 4) + 1 = 9 - a
Substitute variable.
3(5 - 4) + 1 = 9 - 5
Subtract inside parenthesis.
3(1) + 1 = 9 - 5
Multiply 3 and 1.
3 + 1 = 9 - 5
Add 3 and 1.
4 = 9 - 5
Subtract 5 from 9.
4 = 4.
