Solve for x:5 x + 3 (x + 4) = -20
3 (x + 4) = 3 x + 12:3 x + 12 + 5 x = -20
Grouping like terms, 5 x + 3 x + 12 = (5 x + 3 x) + 12:(5 x + 3 x) + 12 = -20
5 x + 3 x = 8 x:8 x + 12 = -20
Subtract 12 from both sides:8 x + (12 - 12) = -12 - 20
12 - 12 = 0:8 x = -20 - 12
-20 - 12 = -32:8 x = -32
Divide both sides of 8 x = -32 by 8:(8 x)/8 = (-32)/8
8/8 = 1:x = (-32)/8
The gcd of -32 and 8 is 8, so (-32)/8 = (8 (-4))/(8×1) = 8/8×-4 = -4:Answer: x = -4