Answer:
n = -1
Explanation:
Solve for n: 
1 - 2 n = 3 (n + 2) 
 
Expand out terms of the right-hand side: 
1 - 2 n = 3 n + 6 
 
Subtract 3 n from both sides: 
1 + (-2 n - 3 n) = (3 n - 3 n) + 6 
 
-2 n - 3 n = -5 n: 
-5 n + 1 = (3 n - 3 n) + 6 
 
3 n - 3 n = 0: 
1 - 5 n = 6 
 
Subtract 1 from both sides: 
(1 - 1) - 5 n = 6 - 1 
 
1 - 1 = 0: 
-5 n = 6 - 1 
 
6 - 1 = 5: 
-5 n = 5 
 
Divide both sides of -5 n = 5 by -5: 
(-5 n)/(-5) = 5/(-5) 
 
(-5)/(-5) = 1: 
n = 5/(-5) 
 
The gcd of 5 and -5 is 5, so 5/(-5) = (5×1)/(5 (-1)) = 5/5×1/(-1) = 1/(-1): 
n = 1/(-1) 
 
1/(-1) = -1: 
Answer: n = -1