Solve 5x + 12 = 87
The solution of 5x + 12 = 87 is x = 15.
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 = 15 back into the equation.
LaTeX source of the formulas on this page
\[ 5x + 12 = 87\ \Rightarrow\ x = 15 \]
\[ 5x + 12 = 87 \]
\[ 5x + 12 - 12 = 87 - 12 \ \Rightarrow\ 5x = 75 \]
\[ \frac{5x}{5} = \frac{75}{5} \ \Rightarrow\ x = 15 \]
\[ 5\cdot15 + 12 = 75 + 12 = 87 \checkmark \]Trying values of x in 5x + 12 = 87
| x | 5x + 12 | Equals 87? |
|---|---|---|
| 13 | 77 | no |
| 14 | 82 | no |
| 15 | 87 | yes |
| 16 | 92 | no |
| 17 | 97 | no |
Questions
What is x in 5x + 12 = 87?
The solution of 5x + 12 = 87 is x = 15.
How do you solve 5x + 12 = 87?
Subtract 12 from both sides to get 5x = 75, then divide both sides by 5 to get x = 15.
How do I check the answer?
Replace x by 15: 5(15) + 12 = 87, which is 87.