Solve 12x − 9 = 123

The solution of 12x − 9 = 123 is x = 11.

12x - 9 = 123\ \Rightarrow\ x = 11

Explain it step by step in chat Make a short video of it

The lines y = 12x − 9 and y = 123 meet at x = 11. The solution of the equation is the x-coordinate of the point where the two sides are equal.

How to work it out

1
The goal is to get x alone. Undo the operations in the opposite order: first the subtraction, then the multiplication.
$12x - 9 = 123$
2
Add 9 to both sides:
$12x - 9 + 9 = 123 + 9 \ \Rightarrow\ 12x = 132$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{132}{12} \ \Rightarrow\ x = 11$
4
Check: put x = 11 back into the equation.
$12\cdot11 - 9 = 132 - 9 = 123 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 9 = 123\ \Rightarrow\ x = 11 \]
\[ 12x - 9 = 123 \]
\[ 12x - 9 + 9 = 123 + 9 \ \Rightarrow\ 12x = 132 \]
\[ \frac{12x}{12} = \frac{132}{12} \ \Rightarrow\ x = 11 \]
\[ 12\cdot11 - 9 = 132 - 9 = 123 \checkmark \]

Trying values of x in 12x − 9 = 123

x	12x − 9	Equals 123?
9	99	no
10	111	no
11	123	yes
12	135	no
13	147	no

Questions

What is x in 12x − 9 = 123?

The solution of 12x − 9 = 123 is x = 11.

How do you solve 12x − 9 = 123?

Add 9 to both sides to get 12x = 132, then divide both sides by 12 to get x = 11.

How do I check the answer?

Replace x by 11: 12(11) − 9 = 123, which is 123.

Solve 12x − 9 = 123

How to work it out

Trying values of x in 12x − 9 = 123

Questions

Similar equations