Solve 7x − 5 = 86

The solution of 7x − 5 = 86 is x = 13.

7x - 5 = 86\ \Rightarrow\ x = 13

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The lines y = 7x − 5 and y = 86 meet at x = 13. 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.
$7x - 5 = 86$
2
Add 5 to both sides:
$7x - 5 + 5 = 86 + 5 \ \Rightarrow\ 7x = 91$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{91}{7} \ \Rightarrow\ x = 13$
4
Check: put x = 13 back into the equation.
$7\cdot13 - 5 = 91 - 5 = 86 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 5 = 86\ \Rightarrow\ x = 13 \]
\[ 7x - 5 = 86 \]
\[ 7x - 5 + 5 = 86 + 5 \ \Rightarrow\ 7x = 91 \]
\[ \frac{7x}{7} = \frac{91}{7} \ \Rightarrow\ x = 13 \]
\[ 7\cdot13 - 5 = 91 - 5 = 86 \checkmark \]

Trying values of x in 7x − 5 = 86

x	7x − 5	Equals 86?
11	72	no
12	79	no
13	86	yes
14	93	no
15	100	no

Questions

What is x in 7x − 5 = 86?

The solution of 7x − 5 = 86 is x = 13.

How do you solve 7x − 5 = 86?

Add 5 to both sides to get 7x = 91, then divide both sides by 7 to get x = 13.

How do I check the answer?

Replace x by 13: 7(13) − 5 = 86, which is 86.

Solve 7x − 5 = 86

How to work it out

Trying values of x in 7x − 5 = 86

Questions

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