Solve 9x − 8 = 55

The solution of 9x − 8 = 55 is x = 7.

9x - 8 = 55\ \Rightarrow\ x = 7

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The lines y = 9x − 8 and y = 55 meet at x = 7. 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.
$9x - 8 = 55$
2
Add 8 to both sides:
$9x - 8 + 8 = 55 + 8 \ \Rightarrow\ 9x = 63$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{63}{9} \ \Rightarrow\ x = 7$
4
Check: put x = 7 back into the equation.
$9\cdot7 - 8 = 63 - 8 = 55 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 8 = 55\ \Rightarrow\ x = 7 \]
\[ 9x - 8 = 55 \]
\[ 9x - 8 + 8 = 55 + 8 \ \Rightarrow\ 9x = 63 \]
\[ \frac{9x}{9} = \frac{63}{9} \ \Rightarrow\ x = 7 \]
\[ 9\cdot7 - 8 = 63 - 8 = 55 \checkmark \]

Trying values of x in 9x − 8 = 55

x	9x − 8	Equals 55?
5	37	no
6	46	no
7	55	yes
8	64	no
9	73	no

Questions

What is x in 9x − 8 = 55?

The solution of 9x − 8 = 55 is x = 7.

How do you solve 9x − 8 = 55?

Add 8 to both sides to get 9x = 63, then divide both sides by 9 to get x = 7.

How do I check the answer?

Replace x by 7: 9(7) − 8 = 55, which is 55.

Solve 9x − 8 = 55

How to work it out

Trying values of x in 9x − 8 = 55

Questions

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