Solve 9x − 13 = 140

The solution of 9x − 13 = 140 is x = 17.

9x - 13 = 140\ \Rightarrow\ x = 17

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The lines y = 9x − 13 and y = 140 meet at x = 17. 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.
$9x - 13 = 140$
2
Add 13 to both sides:
$9x - 13 + 13 = 140 + 13 \ \Rightarrow\ 9x = 153$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{153}{9} \ \Rightarrow\ x = 17$
4
Check: put x = 17 back into the equation.
$9\cdot17 - 13 = 153 - 13 = 140 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 13 = 140\ \Rightarrow\ x = 17 \]
\[ 9x - 13 = 140 \]
\[ 9x - 13 + 13 = 140 + 13 \ \Rightarrow\ 9x = 153 \]
\[ \frac{9x}{9} = \frac{153}{9} \ \Rightarrow\ x = 17 \]
\[ 9\cdot17 - 13 = 153 - 13 = 140 \checkmark \]

Trying values of x in 9x − 13 = 140

x	9x − 13	Equals 140?
15	122	no
16	131	no
17	140	yes
18	149	no
19	158	no

Questions

What is x in 9x − 13 = 140?

The solution of 9x − 13 = 140 is x = 17.

How do you solve 9x − 13 = 140?

Add 13 to both sides to get 9x = 153, then divide both sides by 9 to get x = 17.

How do I check the answer?

Replace x by 17: 9(17) − 13 = 140, which is 140.

Solve 9x − 13 = 140

How to work it out

Trying values of x in 9x − 13 = 140

Questions

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