Solve 5x + 12 = 77
The solution of 5x + 12 = 77 is x = 13.
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 12 from both sides:
- 3
Divide both sides by 5:
- 4
Check: put x = 13 back into the equation.
LaTeX source of the formulas on this page
\[ 5x + 12 = 77\ \Rightarrow\ x = 13 \]
\[ 5x + 12 = 77 \]
\[ 5x + 12 - 12 = 77 - 12 \ \Rightarrow\ 5x = 65 \]
\[ \frac{5x}{5} = \frac{65}{5} \ \Rightarrow\ x = 13 \]
\[ 5\cdot13 + 12 = 65 + 12 = 77 \checkmark \]Trying values of x in 5x + 12 = 77
| x | 5x + 12 | Equals 77? |
|---|---|---|
| 11 | 67 | no |
| 12 | 72 | no |
| 13 | 77 | yes |
| 14 | 82 | no |
| 15 | 87 | no |
Questions
What is x in 5x + 12 = 77?
The solution of 5x + 12 = 77 is x = 13.
How do you solve 5x + 12 = 77?
Subtract 12 from both sides to get 5x = 65, then divide both sides by 5 to get x = 13.
How do I check the answer?
Replace x by 13: 5(13) + 12 = 77, which is 77.