Solve 8x − 13 = 139

The solution of 8x − 13 = 139 is x = 19.

8x - 13 = 139\ \Rightarrow\ x = 19

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The lines y = 8x − 13 and y = 139 meet at x = 19. 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.
$8x - 13 = 139$
2
Add 13 to both sides:
$8x - 13 + 13 = 139 + 13 \ \Rightarrow\ 8x = 152$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{152}{8} \ \Rightarrow\ x = 19$
4
Check: put x = 19 back into the equation.
$8\cdot19 - 13 = 152 - 13 = 139 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 13 = 139\ \Rightarrow\ x = 19 \]
\[ 8x - 13 = 139 \]
\[ 8x - 13 + 13 = 139 + 13 \ \Rightarrow\ 8x = 152 \]
\[ \frac{8x}{8} = \frac{152}{8} \ \Rightarrow\ x = 19 \]
\[ 8\cdot19 - 13 = 152 - 13 = 139 \checkmark \]

Trying values of x in 8x − 13 = 139

x	8x − 13	Equals 139?
17	123	no
18	131	no
19	139	yes
20	147	no
21	155	no

Questions

What is x in 8x − 13 = 139?

The solution of 8x − 13 = 139 is x = 19.

How do you solve 8x − 13 = 139?

Add 13 to both sides to get 8x = 152, then divide both sides by 8 to get x = 19.

How do I check the answer?

Replace x by 19: 8(19) − 13 = 139, which is 139.

Solve 8x − 13 = 139

How to work it out

Trying values of x in 8x − 13 = 139

Questions

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