9x + -4 = 77 Reorder the terms: -4 + 9x = 77 Solving -4 + 9x = 77 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '4' to each side of the equation. -4 + 4 + 9x = 77 + 4 Combine like terms: -4 + 4 = 0 0 + 9x = 77 + 4 9x = 77 + 4 Combine like terms: 77 + 4 = 81 9x = 81 Divide each side by '9'. x = 9 Simplifying x = -9