Solve 12x − 5 = 139

The solution of 12x − 5 = 139 is x = 12.

12x - 5 = 139\ \Rightarrow\ x = 12

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The lines y = 12x − 5 and y = 139 meet at x = 12. 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.
$12x - 5 = 139$
2
Add 5 to both sides:
$12x - 5 + 5 = 139 + 5 \ \Rightarrow\ 12x = 144$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{144}{12} \ \Rightarrow\ x = 12$
4
Check: put x = 12 back into the equation.
$12\cdot12 - 5 = 144 - 5 = 139 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 5 = 139\ \Rightarrow\ x = 12 \]
\[ 12x - 5 = 139 \]
\[ 12x - 5 + 5 = 139 + 5 \ \Rightarrow\ 12x = 144 \]
\[ \frac{12x}{12} = \frac{144}{12} \ \Rightarrow\ x = 12 \]
\[ 12\cdot12 - 5 = 144 - 5 = 139 \checkmark \]

Trying values of x in 12x − 5 = 139

x	12x − 5	Equals 139?
10	115	no
11	127	no
12	139	yes
13	151	no
14	163	no

Questions

What is x in 12x − 5 = 139?

The solution of 12x − 5 = 139 is x = 12.

How do you solve 12x − 5 = 139?

Add 5 to both sides to get 12x = 144, then divide both sides by 12 to get x = 12.

How do I check the answer?

Replace x by 12: 12(12) − 5 = 139, which is 139.

Solve 12x − 5 = 139

How to work it out

Trying values of x in 12x − 5 = 139

Questions

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