Solve 10x + 3 = 123
The solution of 10x + 3 = 123 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 3 from both sides:
- 3
Divide both sides by 10:
- 4
Check: put x = 12 back into the equation.
LaTeX source of the formulas on this page
\[ 10x + 3 = 123\ \Rightarrow\ x = 12 \]
\[ 10x + 3 = 123 \]
\[ 10x + 3 - 3 = 123 - 3 \ \Rightarrow\ 10x = 120 \]
\[ \frac{10x}{10} = \frac{120}{10} \ \Rightarrow\ x = 12 \]
\[ 10\cdot12 + 3 = 120 + 3 = 123 \checkmark \]Trying values of x in 10x + 3 = 123
| x | 10x + 3 | Equals 123? |
|---|---|---|
| 10 | 103 | no |
| 11 | 113 | no |
| 12 | 123 | yes |
| 13 | 133 | no |
| 14 | 143 | no |
Questions
What is x in 10x + 3 = 123?
The solution of 10x + 3 = 123 is x = 12.
How do you solve 10x + 3 = 123?
Subtract 3 from both sides to get 10x = 120, then divide both sides by 10 to get x = 12.
How do I check the answer?
Replace x by 12: 10(12) + 3 = 123, which is 123.