Solve 6x + 8 = 128
The solution of 6x + 8 = 128 is x = 20.
How to work it out
- 1
The goal is to get x alone. Undo the operations in the opposite order: first the addition, then the multiplication.
- 2
Subtract 8 from both sides:
- 3
Divide both sides by 6:
- 4
Check: put x = 20 back into the equation.
LaTeX source of the formulas on this page
\[ 6x + 8 = 128\ \Rightarrow\ x = 20 \]
\[ 6x + 8 = 128 \]
\[ 6x + 8 - 8 = 128 - 8 \ \Rightarrow\ 6x = 120 \]
\[ \frac{6x}{6} = \frac{120}{6} \ \Rightarrow\ x = 20 \]
\[ 6\cdot20 + 8 = 120 + 8 = 128 \checkmark \]Trying values of x in 6x + 8 = 128
| x | 6x + 8 | Equals 128? |
|---|---|---|
| 18 | 116 | no |
| 19 | 122 | no |
| 20 | 128 | yes |
| 21 | 134 | no |
| 22 | 140 | no |
Questions
What is x in 6x + 8 = 128?
The solution of 6x + 8 = 128 is x = 20.
How do you solve 6x + 8 = 128?
Subtract 8 from both sides to get 6x = 120, then divide both sides by 6 to get x = 20.
How do I check the answer?
Replace x by 20: 6(20) + 8 = 128, which is 128.