Solve 11x − 9 = 90

The solution of 11x − 9 = 90 is x = 9.

11x - 9 = 90\ \Rightarrow\ x = 9

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The lines y = 11x − 9 and y = 90 meet at x = 9. 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.
$11x - 9 = 90$
2
Add 9 to both sides:
$11x - 9 + 9 = 90 + 9 \ \Rightarrow\ 11x = 99$
3
Divide both sides by 11:
$\frac{11x}{11} = \frac{99}{11} \ \Rightarrow\ x = 9$
4
Check: put x = 9 back into the equation.
$11\cdot9 - 9 = 99 - 9 = 90 \checkmark$

LaTeX source of the formulas on this page

\[ 11x - 9 = 90\ \Rightarrow\ x = 9 \]
\[ 11x - 9 = 90 \]
\[ 11x - 9 + 9 = 90 + 9 \ \Rightarrow\ 11x = 99 \]
\[ \frac{11x}{11} = \frac{99}{11} \ \Rightarrow\ x = 9 \]
\[ 11\cdot9 - 9 = 99 - 9 = 90 \checkmark \]

Trying values of x in 11x − 9 = 90

x	11x − 9	Equals 90?
7	68	no
8	79	no
9	90	yes
10	101	no
11	112	no

Questions

What is x in 11x − 9 = 90?

The solution of 11x − 9 = 90 is x = 9.

How do you solve 11x − 9 = 90?

Add 9 to both sides to get 11x = 99, then divide both sides by 11 to get x = 9.

How do I check the answer?

Replace x by 9: 11(9) − 9 = 90, which is 90.

Solve 11x − 9 = 90

How to work it out

Trying values of x in 11x − 9 = 90

Questions

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