Answer:
b.) All real numbers.
Step-by-step explanation:
4 (<em>a </em>+ 3) = 12 + 4<em>a </em>
4<em>a</em> + 12 = 12 + 4<em>a </em>
4<em>a </em>+ 12 - 12 = 12 + 4<em>a </em>- 12
4<em>a </em>= 4<em>a </em>
4<em>a</em>/4 = 4<em>a</em>/4
0 = 0
All possibilities of other <em>real </em>number can fit into the equation. Hence, the answer is b.) All real numbers.