Solve 4x − 12 = 28

The solution of 4x − 12 = 28 is x = 10.

4x - 12 = 28\ \Rightarrow\ x = 10

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The lines y = 4x − 12 and y = 28 meet at x = 10. 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.
$4x - 12 = 28$
2
Add 12 to both sides:
$4x - 12 + 12 = 28 + 12 \ \Rightarrow\ 4x = 40$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{40}{4} \ \Rightarrow\ x = 10$
4
Check: put x = 10 back into the equation.
$4\cdot10 - 12 = 40 - 12 = 28 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 12 = 28\ \Rightarrow\ x = 10 \]
\[ 4x - 12 = 28 \]
\[ 4x - 12 + 12 = 28 + 12 \ \Rightarrow\ 4x = 40 \]
\[ \frac{4x}{4} = \frac{40}{4} \ \Rightarrow\ x = 10 \]
\[ 4\cdot10 - 12 = 40 - 12 = 28 \checkmark \]

Trying values of x in 4x − 12 = 28

x	4x − 12	Equals 28?
8	20	no
9	24	no
10	28	yes
11	32	no
12	36	no

Questions

What is x in 4x − 12 = 28?

The solution of 4x − 12 = 28 is x = 10.

How do you solve 4x − 12 = 28?

Add 12 to both sides to get 4x = 40, then divide both sides by 4 to get x = 10.

How do I check the answer?

Replace x by 10: 4(10) − 12 = 28, which is 28.

Solve 4x − 12 = 28

How to work it out

Trying values of x in 4x − 12 = 28

Questions

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