Solve 8x + 8 = 80

The solution of 8x + 8 = 80 is x = 9.

8x + 8 = 80\ \Rightarrow\ x = 9

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The lines y = 8x + 8 and y = 80 meet at x = 9. 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 addition, then the multiplication.
$8x + 8 = 80$
2
Subtract 8 from both sides:
$8x + 8 - 8 = 80 - 8 \ \Rightarrow\ 8x = 72$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{72}{8} \ \Rightarrow\ x = 9$
4
Check: put x = 9 back into the equation.
$8\cdot9 + 8 = 72 + 8 = 80 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 8 = 80\ \Rightarrow\ x = 9 \]
\[ 8x + 8 = 80 \]
\[ 8x + 8 - 8 = 80 - 8 \ \Rightarrow\ 8x = 72 \]
\[ \frac{8x}{8} = \frac{72}{8} \ \Rightarrow\ x = 9 \]
\[ 8\cdot9 + 8 = 72 + 8 = 80 \checkmark \]

Trying values of x in 8x + 8 = 80

x	8x + 8	Equals 80?
7	64	no
8	72	no
9	80	yes
10	88	no
11	96	no

Questions

What is x in 8x + 8 = 80?

The solution of 8x + 8 = 80 is x = 9.

How do you solve 8x + 8 = 80?

Subtract 8 from both sides to get 8x = 72, then divide both sides by 8 to get x = 9.

How do I check the answer?

Replace x by 9: 8(9) + 8 = 80, which is 80.

Solve 8x + 8 = 80

How to work it out

Trying values of x in 8x + 8 = 80

Questions

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