Solve for x:
3 x - 18 = 39
Add 18 to both sides:
3 x + (18 - 18) = 18 + 39
18 - 18 = 0:
3 x = 39 + 18
39 + 18 = 57:
3 x = 57
Divide both sides of 3 x = 57 by 3:
(3 x)/3 = 57/3
3/3 = 1:
x = 57/3
The gcd of 57 and 3 is 3, so 57/3 = (3×19)/(3×1) = 3/3×19 = 19:
Answer: x = 19