Solve 8x − 8 = 120

The solution of 8x − 8 = 120 is x = 16.

8x - 8 = 120\ \Rightarrow\ x = 16

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The lines y = 8x − 8 and y = 120 meet at x = 16. 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.
$8x - 8 = 120$
2
Add 8 to both sides:
$8x - 8 + 8 = 120 + 8 \ \Rightarrow\ 8x = 128$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{128}{8} \ \Rightarrow\ x = 16$
4
Check: put x = 16 back into the equation.
$8\cdot16 - 8 = 128 - 8 = 120 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 8 = 120\ \Rightarrow\ x = 16 \]
\[ 8x - 8 = 120 \]
\[ 8x - 8 + 8 = 120 + 8 \ \Rightarrow\ 8x = 128 \]
\[ \frac{8x}{8} = \frac{128}{8} \ \Rightarrow\ x = 16 \]
\[ 8\cdot16 - 8 = 128 - 8 = 120 \checkmark \]

Trying values of x in 8x − 8 = 120

x	8x − 8	Equals 120?
14	104	no
15	112	no
16	120	yes
17	128	no
18	136	no

Questions

What is x in 8x − 8 = 120?

The solution of 8x − 8 = 120 is x = 16.

How do you solve 8x − 8 = 120?

Add 8 to both sides to get 8x = 128, then divide both sides by 8 to get x = 16.

How do I check the answer?

Replace x by 16: 8(16) − 8 = 120, which is 120.

Solve 8x − 8 = 120

How to work it out

Trying values of x in 8x − 8 = 120

Questions

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