Solve 3x − 9 = 33

The solution of 3x − 9 = 33 is x = 14.

3x - 9 = 33\ \Rightarrow\ x = 14

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The lines y = 3x − 9 and y = 33 meet at x = 14. 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.
$3x - 9 = 33$
2
Add 9 to both sides:
$3x - 9 + 9 = 33 + 9 \ \Rightarrow\ 3x = 42$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{42}{3} \ \Rightarrow\ x = 14$
4
Check: put x = 14 back into the equation.
$3\cdot14 - 9 = 42 - 9 = 33 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 9 = 33\ \Rightarrow\ x = 14 \]
\[ 3x - 9 = 33 \]
\[ 3x - 9 + 9 = 33 + 9 \ \Rightarrow\ 3x = 42 \]
\[ \frac{3x}{3} = \frac{42}{3} \ \Rightarrow\ x = 14 \]
\[ 3\cdot14 - 9 = 42 - 9 = 33 \checkmark \]

Trying values of x in 3x − 9 = 33

x	3x − 9	Equals 33?
12	27	no
13	30	no
14	33	yes
15	36	no
16	39	no

Questions

What is x in 3x − 9 = 33?

The solution of 3x − 9 = 33 is x = 14.

How do you solve 3x − 9 = 33?

Add 9 to both sides to get 3x = 42, then divide both sides by 3 to get x = 14.

How do I check the answer?

Replace x by 14: 3(14) − 9 = 33, which is 33.

Solve 3x − 9 = 33

How to work it out

Trying values of x in 3x − 9 = 33

Questions

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