Solve 10x − 13 = 87

The solution of 10x − 13 = 87 is x = 10.

10x - 13 = 87\ \Rightarrow\ x = 10

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The lines y = 10x − 13 and y = 87 meet at x = 10. 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.
$10x - 13 = 87$
2
Add 13 to both sides:
$10x - 13 + 13 = 87 + 13 \ \Rightarrow\ 10x = 100$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{100}{10} \ \Rightarrow\ x = 10$
4
Check: put x = 10 back into the equation.
$10\cdot10 - 13 = 100 - 13 = 87 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 13 = 87\ \Rightarrow\ x = 10 \]
\[ 10x - 13 = 87 \]
\[ 10x - 13 + 13 = 87 + 13 \ \Rightarrow\ 10x = 100 \]
\[ \frac{10x}{10} = \frac{100}{10} \ \Rightarrow\ x = 10 \]
\[ 10\cdot10 - 13 = 100 - 13 = 87 \checkmark \]

Trying values of x in 10x − 13 = 87

x	10x − 13	Equals 87?
8	67	no
9	77	no
10	87	yes
11	97	no
12	107	no

Questions

What is x in 10x − 13 = 87?

The solution of 10x − 13 = 87 is x = 10.

How do you solve 10x − 13 = 87?

Add 13 to both sides to get 10x = 100, then divide both sides by 10 to get x = 10.

How do I check the answer?

Replace x by 10: 10(10) − 13 = 87, which is 87.

Solve 10x − 13 = 87

How to work it out

Trying values of x in 10x − 13 = 87

Questions

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