Solve 4x − 4 = 76

The solution of 4x − 4 = 76 is x = 20.

4x - 4 = 76\ \Rightarrow\ x = 20

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The lines y = 4x − 4 and y = 76 meet at x = 20. 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.
$4x - 4 = 76$
2
Add 4 to both sides:
$4x - 4 + 4 = 76 + 4 \ \Rightarrow\ 4x = 80$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{80}{4} \ \Rightarrow\ x = 20$
4
Check: put x = 20 back into the equation.
$4\cdot20 - 4 = 80 - 4 = 76 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 4 = 76\ \Rightarrow\ x = 20 \]
\[ 4x - 4 = 76 \]
\[ 4x - 4 + 4 = 76 + 4 \ \Rightarrow\ 4x = 80 \]
\[ \frac{4x}{4} = \frac{80}{4} \ \Rightarrow\ x = 20 \]
\[ 4\cdot20 - 4 = 80 - 4 = 76 \checkmark \]

Trying values of x in 4x − 4 = 76

x	4x − 4	Equals 76?
18	68	no
19	72	no
20	76	yes
21	80	no
22	84	no

Questions

What is x in 4x − 4 = 76?

The solution of 4x − 4 = 76 is x = 20.

How do you solve 4x − 4 = 76?

Add 4 to both sides to get 4x = 80, then divide both sides by 4 to get x = 20.

How do I check the answer?

Replace x by 20: 4(20) − 4 = 76, which is 76.

Solve 4x − 4 = 76

How to work it out

Trying values of x in 4x − 4 = 76

Questions

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