Solve 9x − 7 = 155

The solution of 9x − 7 = 155 is x = 18.

9x - 7 = 155\ \Rightarrow\ x = 18

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The lines y = 9x − 7 and y = 155 meet at x = 18. 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.
$9x - 7 = 155$
2
Add 7 to both sides:
$9x - 7 + 7 = 155 + 7 \ \Rightarrow\ 9x = 162$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{162}{9} \ \Rightarrow\ x = 18$
4
Check: put x = 18 back into the equation.
$9\cdot18 - 7 = 162 - 7 = 155 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 7 = 155\ \Rightarrow\ x = 18 \]
\[ 9x - 7 = 155 \]
\[ 9x - 7 + 7 = 155 + 7 \ \Rightarrow\ 9x = 162 \]
\[ \frac{9x}{9} = \frac{162}{9} \ \Rightarrow\ x = 18 \]
\[ 9\cdot18 - 7 = 162 - 7 = 155 \checkmark \]

Trying values of x in 9x − 7 = 155

x	9x − 7	Equals 155?
16	137	no
17	146	no
18	155	yes
19	164	no
20	173	no

Questions

What is x in 9x − 7 = 155?

The solution of 9x − 7 = 155 is x = 18.

How do you solve 9x − 7 = 155?

Add 7 to both sides to get 9x = 162, then divide both sides by 9 to get x = 18.

How do I check the answer?

Replace x by 18: 9(18) − 7 = 155, which is 155.

Solve 9x − 7 = 155

How to work it out

Trying values of x in 9x − 7 = 155

Questions

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