Solve 6x − 15 = 57

The solution of 6x − 15 = 57 is x = 12.

6x - 15 = 57\ \Rightarrow\ x = 12

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The lines y = 6x − 15 and y = 57 meet at x = 12. 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.
$6x - 15 = 57$
2
Add 15 to both sides:
$6x - 15 + 15 = 57 + 15 \ \Rightarrow\ 6x = 72$
3
Divide both sides by 6:
$\frac{6x}{6} = \frac{72}{6} \ \Rightarrow\ x = 12$
4
Check: put x = 12 back into the equation.
$6\cdot12 - 15 = 72 - 15 = 57 \checkmark$

LaTeX source of the formulas on this page

\[ 6x - 15 = 57\ \Rightarrow\ x = 12 \]
\[ 6x - 15 = 57 \]
\[ 6x - 15 + 15 = 57 + 15 \ \Rightarrow\ 6x = 72 \]
\[ \frac{6x}{6} = \frac{72}{6} \ \Rightarrow\ x = 12 \]
\[ 6\cdot12 - 15 = 72 - 15 = 57 \checkmark \]

Trying values of x in 6x − 15 = 57

x	6x − 15	Equals 57?
10	45	no
11	51	no
12	57	yes
13	63	no
14	69	no

Questions

What is x in 6x − 15 = 57?

The solution of 6x − 15 = 57 is x = 12.

How do you solve 6x − 15 = 57?

Add 15 to both sides to get 6x = 72, then divide both sides by 6 to get x = 12.

How do I check the answer?

Replace x by 12: 6(12) − 15 = 57, which is 57.

Solve 6x − 15 = 57

How to work it out

Trying values of x in 6x − 15 = 57

Questions

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