Solve 7x + 5 = 138
The solution of 7x + 5 = 138 is x = 19.
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 5 from both sides:
- 3
Divide both sides by 7:
- 4
Check: put x = 19 back into the equation.
LaTeX source of the formulas on this page
\[ 7x + 5 = 138\ \Rightarrow\ x = 19 \]
\[ 7x + 5 = 138 \]
\[ 7x + 5 - 5 = 138 - 5 \ \Rightarrow\ 7x = 133 \]
\[ \frac{7x}{7} = \frac{133}{7} \ \Rightarrow\ x = 19 \]
\[ 7\cdot19 + 5 = 133 + 5 = 138 \checkmark \]Trying values of x in 7x + 5 = 138
| x | 7x + 5 | Equals 138? |
|---|---|---|
| 17 | 124 | no |
| 18 | 131 | no |
| 19 | 138 | yes |
| 20 | 145 | no |
| 21 | 152 | no |
Questions
What is x in 7x + 5 = 138?
The solution of 7x + 5 = 138 is x = 19.
How do you solve 7x + 5 = 138?
Subtract 5 from both sides to get 7x = 133, then divide both sides by 7 to get x = 19.
How do I check the answer?
Replace x by 19: 7(19) + 5 = 138, which is 138.