Solve 8x − 5 = 155

The solution of 8x − 5 = 155 is x = 20.

8x - 5 = 155\ \Rightarrow\ x = 20

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The lines y = 8x − 5 and y = 155 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.
$8x - 5 = 155$
2
Add 5 to both sides:
$8x - 5 + 5 = 155 + 5 \ \Rightarrow\ 8x = 160$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{160}{8} \ \Rightarrow\ x = 20$
4
Check: put x = 20 back into the equation.
$8\cdot20 - 5 = 160 - 5 = 155 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 5 = 155\ \Rightarrow\ x = 20 \]
\[ 8x - 5 = 155 \]
\[ 8x - 5 + 5 = 155 + 5 \ \Rightarrow\ 8x = 160 \]
\[ \frac{8x}{8} = \frac{160}{8} \ \Rightarrow\ x = 20 \]
\[ 8\cdot20 - 5 = 160 - 5 = 155 \checkmark \]

Trying values of x in 8x − 5 = 155

x	8x − 5	Equals 155?
18	139	no
19	147	no
20	155	yes
21	163	no
22	171	no

Questions

What is x in 8x − 5 = 155?

The solution of 8x − 5 = 155 is x = 20.

How do you solve 8x − 5 = 155?

Add 5 to both sides to get 8x = 160, then divide both sides by 8 to get x = 20.

How do I check the answer?

Replace x by 20: 8(20) − 5 = 155, which is 155.

Solve 8x − 5 = 155

How to work it out

Trying values of x in 8x − 5 = 155

Questions

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