Answer:
x= -1/12
Step-by-step explanation:
n in (-oo:+oo)
(1/2)*n-3 = 6 // - 6
(1/2)*n-6-3 = 0
1/2*n-9 = 0 // + 9
1/2*n = 9 // : 1/2
n = 9/1/2
n = 18