Solve.
4(a+3)=12+4a
a. -3
b. -1
c. no solution
d. all real numbers

4 (a + 3) = 12 + 4a   Use the Distributive Property
  4a + 12 = 12 + 4a   Subtract 4a from both sides
          12 = 12

Since the equation is the same on both sides, any number will work as a. So, the answer is D. All Real Numbers.