Solve 8x − 15 = 145

The solution of 8x − 15 = 145 is x = 20.

8x - 15 = 145\ \Rightarrow\ x = 20

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The lines y = 8x − 15 and y = 145 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.
$8x - 15 = 145$
2
Add 15 to both sides:
$8x - 15 + 15 = 145 + 15 \ \Rightarrow\ 8x = 160$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{160}{8} \ \Rightarrow\ x = 20$
4
Check: put x = 20 back into the equation.
$8\cdot20 - 15 = 160 - 15 = 145 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 15 = 145\ \Rightarrow\ x = 20 \]
\[ 8x - 15 = 145 \]
\[ 8x - 15 + 15 = 145 + 15 \ \Rightarrow\ 8x = 160 \]
\[ \frac{8x}{8} = \frac{160}{8} \ \Rightarrow\ x = 20 \]
\[ 8\cdot20 - 15 = 160 - 15 = 145 \checkmark \]

Trying values of x in 8x − 15 = 145

x	8x − 15	Equals 145?
18	129	no
19	137	no
20	145	yes
21	153	no
22	161	no

Questions

What is x in 8x − 15 = 145?

The solution of 8x − 15 = 145 is x = 20.

How do you solve 8x − 15 = 145?

Add 15 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) − 15 = 145, which is 145.

Solve 8x − 15 = 145

How to work it out

Trying values of x in 8x − 15 = 145

Questions

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