Solve 7x + 3 = 115
The solution of 7x + 3 = 115 is x = 16.
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 3 from both sides:
- 3
Divide both sides by 7:
- 4
Check: put x = 16 back into the equation.
LaTeX source of the formulas on this page
\[ 7x + 3 = 115\ \Rightarrow\ x = 16 \]
\[ 7x + 3 = 115 \]
\[ 7x + 3 - 3 = 115 - 3 \ \Rightarrow\ 7x = 112 \]
\[ \frac{7x}{7} = \frac{112}{7} \ \Rightarrow\ x = 16 \]
\[ 7\cdot16 + 3 = 112 + 3 = 115 \checkmark \]Trying values of x in 7x + 3 = 115
| x | 7x + 3 | Equals 115? |
|---|---|---|
| 14 | 101 | no |
| 15 | 108 | no |
| 16 | 115 | yes |
| 17 | 122 | no |
| 18 | 129 | no |
Questions
What is x in 7x + 3 = 115?
The solution of 7x + 3 = 115 is x = 16.
How do you solve 7x + 3 = 115?
Subtract 3 from both sides to get 7x = 112, then divide both sides by 7 to get x = 16.
How do I check the answer?
Replace x by 16: 7(16) + 3 = 115, which is 115.