36x+660=-3x

Solve for x:

• Start: 36x + 660 = -3x
• Add 3x to both sides: 39x + 660 = 0
• Subtract 660: 39x = -660
• Divide by 39: x = -660/39 = -220/13
• Decimal form: x ≈ -16.9231

Check: 36x + 660 = -3x holds for x = -220/13.