Solve 7x − 13 = 99

The solution of 7x − 13 = 99 is x = 16.

7x - 13 = 99\ \Rightarrow\ x = 16

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The lines y = 7x − 13 and y = 99 meet at x = 16. 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.
$7x - 13 = 99$
2
Add 13 to both sides:
$7x - 13 + 13 = 99 + 13 \ \Rightarrow\ 7x = 112$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{112}{7} \ \Rightarrow\ x = 16$
4
Check: put x = 16 back into the equation.
$7\cdot16 - 13 = 112 - 13 = 99 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 13 = 99\ \Rightarrow\ x = 16 \]
\[ 7x - 13 = 99 \]
\[ 7x - 13 + 13 = 99 + 13 \ \Rightarrow\ 7x = 112 \]
\[ \frac{7x}{7} = \frac{112}{7} \ \Rightarrow\ x = 16 \]
\[ 7\cdot16 - 13 = 112 - 13 = 99 \checkmark \]

Trying values of x in 7x − 13 = 99

x	7x − 13	Equals 99?
14	85	no
15	92	no
16	99	yes
17	106	no
18	113	no

Questions

What is x in 7x − 13 = 99?

The solution of 7x − 13 = 99 is x = 16.

How do you solve 7x − 13 = 99?

Add 13 to both sides to get 7x = 112, then divide both sides by 7 to get x = 16.

How do I check the answer?

Replace x by 16: 7(16) − 13 = 99, which is 99.

Solve 7x − 13 = 99

How to work it out

Trying values of x in 7x − 13 = 99

Questions

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