Solve 12x − 15 = 57

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

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

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The lines y = 12x − 15 and y = 57 meet at x = 6. 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.
$12x - 15 = 57$
2
Add 15 to both sides:
$12x - 15 + 15 = 57 + 15 \ \Rightarrow\ 12x = 72$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{72}{12} \ \Rightarrow\ x = 6$
4
Check: put x = 6 back into the equation.
$12\cdot6 - 15 = 72 - 15 = 57 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 15 = 57\ \Rightarrow\ x = 6 \]
\[ 12x - 15 = 57 \]
\[ 12x - 15 + 15 = 57 + 15 \ \Rightarrow\ 12x = 72 \]
\[ \frac{12x}{12} = \frac{72}{12} \ \Rightarrow\ x = 6 \]
\[ 12\cdot6 - 15 = 72 - 15 = 57 \checkmark \]

Trying values of x in 12x − 15 = 57

x	12x − 15	Equals 57?
4	33	no
5	45	no
6	57	yes
7	69	no
8	81	no

Questions

What is x in 12x − 15 = 57?

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

How do you solve 12x − 15 = 57?

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

How do I check the answer?

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

Solve 12x − 15 = 57

How to work it out

Trying values of x in 12x − 15 = 57

Questions

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