It is known that the solution of the equation 2aX = [a + 3] x + 12 about X is a natural number, and the value of integer a is determined

It is known that the solution of the equation 2aX = [a + 3] x + 12 about X is a natural number, and the value of integer a is determined

2ax=【a+3】x+12
(2a-a-3)x=12
(a-3)x=12
X = 12 / (A-3) = natural number
a-3=1,2,3,4,6,12
therefore
a=4,5,6,7,9,15.