Question

12+4ori(36:6-6)-a=72:(4ori6:3)

Answer 1

$12+4 \cdot (36:6-6)-a=72:(4 \cdot 6:3 \\ 12+4 \cdot (6-6)-a=72:(24:3) \\ 12+4 \cdot 0-a=72:8 \\ 12+0-a=9 \\ 12-a=9 \\ a=12-9 \\ \boxed{a=3}$