Solve 9x − 9 = 108

The solution of 9x − 9 = 108 is x = 13.

9x - 9 = 108\ \Rightarrow\ x = 13

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The lines y = 9x − 9 and y = 108 meet at x = 13. 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.
$9x - 9 = 108$
2
Add 9 to both sides:
$9x - 9 + 9 = 108 + 9 \ \Rightarrow\ 9x = 117$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{117}{9} \ \Rightarrow\ x = 13$
4
Check: put x = 13 back into the equation.
$9\cdot13 - 9 = 117 - 9 = 108 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 9 = 108\ \Rightarrow\ x = 13 \]
\[ 9x - 9 = 108 \]
\[ 9x - 9 + 9 = 108 + 9 \ \Rightarrow\ 9x = 117 \]
\[ \frac{9x}{9} = \frac{117}{9} \ \Rightarrow\ x = 13 \]
\[ 9\cdot13 - 9 = 117 - 9 = 108 \checkmark \]

Trying values of x in 9x − 9 = 108

x	9x − 9	Equals 108?
11	90	no
12	99	no
13	108	yes
14	117	no
15	126	no

Questions

What is x in 9x − 9 = 108?

The solution of 9x − 9 = 108 is x = 13.

How do you solve 9x − 9 = 108?

Add 9 to both sides to get 9x = 117, then divide both sides by 9 to get x = 13.

How do I check the answer?

Replace x by 13: 9(13) − 9 = 108, which is 108.

Solve 9x − 9 = 108

How to work it out

Trying values of x in 9x − 9 = 108

Questions

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