Solve 12x − 3 = 129

The solution of 12x − 3 = 129 is x = 11.

12x - 3 = 129\ \Rightarrow\ x = 11

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The lines y = 12x − 3 and y = 129 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.
$12x - 3 = 129$
2
Add 3 to both sides:
$12x - 3 + 3 = 129 + 3 \ \Rightarrow\ 12x = 132$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{132}{12} \ \Rightarrow\ x = 11$
4
Check: put x = 11 back into the equation.
$12\cdot11 - 3 = 132 - 3 = 129 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 3 = 129\ \Rightarrow\ x = 11 \]
\[ 12x - 3 = 129 \]
\[ 12x - 3 + 3 = 129 + 3 \ \Rightarrow\ 12x = 132 \]
\[ \frac{12x}{12} = \frac{132}{12} \ \Rightarrow\ x = 11 \]
\[ 12\cdot11 - 3 = 132 - 3 = 129 \checkmark \]

Trying values of x in 12x − 3 = 129

x	12x − 3	Equals 129?
9	105	no
10	117	no
11	129	yes
12	141	no
13	153	no

Questions

What is x in 12x − 3 = 129?

The solution of 12x − 3 = 129 is x = 11.

How do you solve 12x − 3 = 129?

Add 3 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) − 3 = 129, which is 129.

Solve 12x − 3 = 129

How to work it out

Trying values of x in 12x − 3 = 129

Questions

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