Solve 9x + 7 = 115
The solution of 9x + 7 = 115 is x = 12.
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 7 from both sides:
- 3
Divide both sides by 9:
- 4
Check: put x = 12 back into the equation.
LaTeX source of the formulas on this page
\[ 9x + 7 = 115\ \Rightarrow\ x = 12 \]
\[ 9x + 7 = 115 \]
\[ 9x + 7 - 7 = 115 - 7 \ \Rightarrow\ 9x = 108 \]
\[ \frac{9x}{9} = \frac{108}{9} \ \Rightarrow\ x = 12 \]
\[ 9\cdot12 + 7 = 108 + 7 = 115 \checkmark \]Trying values of x in 9x + 7 = 115
| x | 9x + 7 | Equals 115? |
|---|---|---|
| 10 | 97 | no |
| 11 | 106 | no |
| 12 | 115 | yes |
| 13 | 124 | no |
| 14 | 133 | no |
Questions
What is x in 9x + 7 = 115?
The solution of 9x + 7 = 115 is x = 12.
How do you solve 9x + 7 = 115?
Subtract 7 from both sides to get 9x = 108, then divide both sides by 9 to get x = 12.
How do I check the answer?
Replace x by 12: 9(12) + 7 = 115, which is 115.