Solve 9x − 8 = 28

The solution of 9x − 8 = 28 is x = 4.

9x - 8 = 28\ \Rightarrow\ x = 4

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The lines y = 9x − 8 and y = 28 meet at x = 4. 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.
$9x - 8 = 28$
2
Add 8 to both sides:
$9x - 8 + 8 = 28 + 8 \ \Rightarrow\ 9x = 36$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{36}{9} \ \Rightarrow\ x = 4$
4
Check: put x = 4 back into the equation.
$9\cdot4 - 8 = 36 - 8 = 28 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 8 = 28\ \Rightarrow\ x = 4 \]
\[ 9x - 8 = 28 \]
\[ 9x - 8 + 8 = 28 + 8 \ \Rightarrow\ 9x = 36 \]
\[ \frac{9x}{9} = \frac{36}{9} \ \Rightarrow\ x = 4 \]
\[ 9\cdot4 - 8 = 36 - 8 = 28 \checkmark \]

Trying values of x in 9x − 8 = 28

x	9x − 8	Equals 28?
2	10	no
3	19	no
4	28	yes
5	37	no
6	46	no

Questions

What is x in 9x − 8 = 28?

The solution of 9x − 8 = 28 is x = 4.

How do you solve 9x − 8 = 28?

Add 8 to both sides to get 9x = 36, then divide both sides by 9 to get x = 4.

How do I check the answer?

Replace x by 4: 9(4) − 8 = 28, which is 28.

Solve 9x − 8 = 28

How to work it out

Trying values of x in 9x − 8 = 28

Questions

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