Answer:
x = 6
Explanation:
3 (2 x + 1) + x = -39 
 
3 (2 x + 1) = 6 x + 3: 
6 x + 3 + x = -39 
 
Grouping like terms, 6 x + x + 3 = (6 x + x) + 3: 
(6 x + x) + 3 = -39 
 
6 x + x = 7 x: 
7 x + 3 = -39 
 
Subtract 3 from both sides: 
7 x + (3 - 3) = -3 - 39 
 
3 - 3 = 0: 
7 x = -3 - 39 
 
-3 - 39 = -42: 
7 x = -42 
 
Divide both sides of 7 x = -42 by 7: 
(7 x)/7 = (-42)/7 
 
7/7 = 1: 
x = (-42)/7 
 
The gcd of -42 and 7 is 7, so (-42)/7 = (7 (-6))/(7×1) = 7/7×-6 = -6: 
Answer: x = -6