Solve 6x − 12 = 90

The solution of 6x − 12 = 90 is x = 17.

6x - 12 = 90\ \Rightarrow\ x = 17

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The lines y = 6x − 12 and y = 90 meet at x = 17. 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.
$6x - 12 = 90$
2
Add 12 to both sides:
$6x - 12 + 12 = 90 + 12 \ \Rightarrow\ 6x = 102$
3
Divide both sides by 6:
$\frac{6x}{6} = \frac{102}{6} \ \Rightarrow\ x = 17$
4
Check: put x = 17 back into the equation.
$6\cdot17 - 12 = 102 - 12 = 90 \checkmark$

LaTeX source of the formulas on this page

\[ 6x - 12 = 90\ \Rightarrow\ x = 17 \]
\[ 6x - 12 = 90 \]
\[ 6x - 12 + 12 = 90 + 12 \ \Rightarrow\ 6x = 102 \]
\[ \frac{6x}{6} = \frac{102}{6} \ \Rightarrow\ x = 17 \]
\[ 6\cdot17 - 12 = 102 - 12 = 90 \checkmark \]

Trying values of x in 6x − 12 = 90

x	6x − 12	Equals 90?
15	78	no
16	84	no
17	90	yes
18	96	no
19	102	no

Questions

What is x in 6x − 12 = 90?

The solution of 6x − 12 = 90 is x = 17.

How do you solve 6x − 12 = 90?

Add 12 to both sides to get 6x = 102, then divide both sides by 6 to get x = 17.

How do I check the answer?

Replace x by 17: 6(17) − 12 = 90, which is 90.

Solve 6x − 12 = 90

How to work it out

Trying values of x in 6x − 12 = 90

Questions

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