Algebra · Distribution
Solve 3(x − 4) + 5 = 20
A common mistake is writing 3x − 4 + 5 = 20. The 3 must multiply both terms inside the parentheses, including −4.
- 3x − 12 + 5 = 20Distribute 3 to both terms.
- 3x − 7 = 20Combine −12 and +5.
- 3x = 27Add 7 to both sides.
- x = 9Divide both sides by 3.
Check: substitute 9 into the original equation. 3(9 − 4) + 5 = 15 + 5 = 20.