Solve 12x − 8 = 172

The solution of 12x − 8 = 172 is x = 15.

12x - 8 = 172\ \Rightarrow\ x = 15

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The lines y = 12x − 8 and y = 172 meet at x = 15. 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.
$12x - 8 = 172$
2
Add 8 to both sides:
$12x - 8 + 8 = 172 + 8 \ \Rightarrow\ 12x = 180$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{180}{12} \ \Rightarrow\ x = 15$
4
Check: put x = 15 back into the equation.
$12\cdot15 - 8 = 180 - 8 = 172 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 8 = 172\ \Rightarrow\ x = 15 \]
\[ 12x - 8 = 172 \]
\[ 12x - 8 + 8 = 172 + 8 \ \Rightarrow\ 12x = 180 \]
\[ \frac{12x}{12} = \frac{180}{12} \ \Rightarrow\ x = 15 \]
\[ 12\cdot15 - 8 = 180 - 8 = 172 \checkmark \]

Trying values of x in 12x − 8 = 172

x	12x − 8	Equals 172?
13	148	no
14	160	no
15	172	yes
16	184	no
17	196	no

Questions

What is x in 12x − 8 = 172?

The solution of 12x − 8 = 172 is x = 15.

How do you solve 12x − 8 = 172?

Add 8 to both sides to get 12x = 180, then divide both sides by 12 to get x = 15.

How do I check the answer?

Replace x by 15: 12(15) − 8 = 172, which is 172.

Solve 12x − 8 = 172

How to work it out

Trying values of x in 12x − 8 = 172

Questions

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