Solve 9x − 12 = 69

The solution of 9x − 12 = 69 is x = 9.

9x - 12 = 69\ \Rightarrow\ x = 9

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The lines y = 9x − 12 and y = 69 meet at x = 9. 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.
$9x - 12 = 69$
2
Add 12 to both sides:
$9x - 12 + 12 = 69 + 12 \ \Rightarrow\ 9x = 81$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{81}{9} \ \Rightarrow\ x = 9$
4
Check: put x = 9 back into the equation.
$9\cdot9 - 12 = 81 - 12 = 69 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 12 = 69\ \Rightarrow\ x = 9 \]
\[ 9x - 12 = 69 \]
\[ 9x - 12 + 12 = 69 + 12 \ \Rightarrow\ 9x = 81 \]
\[ \frac{9x}{9} = \frac{81}{9} \ \Rightarrow\ x = 9 \]
\[ 9\cdot9 - 12 = 81 - 12 = 69 \checkmark \]

Trying values of x in 9x − 12 = 69

x	9x − 12	Equals 69?
7	51	no
8	60	no
9	69	yes
10	78	no
11	87	no

Questions

What is x in 9x − 12 = 69?

The solution of 9x − 12 = 69 is x = 9.

How do you solve 9x − 12 = 69?

Add 12 to both sides to get 9x = 81, then divide both sides by 9 to get x = 9.

How do I check the answer?

Replace x by 9: 9(9) − 12 = 69, which is 69.

Solve 9x − 12 = 69

How to work it out

Trying values of x in 9x − 12 = 69

Questions

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