Solve 6x − 15 = 39

The solution of 6x − 15 = 39 is x = 9.

6x - 15 = 39\ \Rightarrow\ x = 9

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The lines y = 6x − 15 and y = 39 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.
$6x - 15 = 39$
2
Add 15 to both sides:
$6x - 15 + 15 = 39 + 15 \ \Rightarrow\ 6x = 54$
3
Divide both sides by 6:
$\frac{6x}{6} = \frac{54}{6} \ \Rightarrow\ x = 9$
4
Check: put x = 9 back into the equation.
$6\cdot9 - 15 = 54 - 15 = 39 \checkmark$

LaTeX source of the formulas on this page

\[ 6x - 15 = 39\ \Rightarrow\ x = 9 \]
\[ 6x - 15 = 39 \]
\[ 6x - 15 + 15 = 39 + 15 \ \Rightarrow\ 6x = 54 \]
\[ \frac{6x}{6} = \frac{54}{6} \ \Rightarrow\ x = 9 \]
\[ 6\cdot9 - 15 = 54 - 15 = 39 \checkmark \]

Trying values of x in 6x − 15 = 39

x	6x − 15	Equals 39?
7	27	no
8	33	no
9	39	yes
10	45	no
11	51	no

Questions

What is x in 6x − 15 = 39?

The solution of 6x − 15 = 39 is x = 9.

How do you solve 6x − 15 = 39?

Add 15 to both sides to get 6x = 54, then divide both sides by 6 to get x = 9.

How do I check the answer?

Replace x by 9: 6(9) − 15 = 39, which is 39.

Solve 6x − 15 = 39

How to work it out

Trying values of x in 6x − 15 = 39

Questions

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