Solve 10x − 15 = 85

The solution of 10x − 15 = 85 is x = 10.

10x - 15 = 85\ \Rightarrow\ x = 10

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The lines y = 10x − 15 and y = 85 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.
$10x - 15 = 85$
2
Add 15 to both sides:
$10x - 15 + 15 = 85 + 15 \ \Rightarrow\ 10x = 100$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{100}{10} \ \Rightarrow\ x = 10$
4
Check: put x = 10 back into the equation.
$10\cdot10 - 15 = 100 - 15 = 85 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 15 = 85\ \Rightarrow\ x = 10 \]
\[ 10x - 15 = 85 \]
\[ 10x - 15 + 15 = 85 + 15 \ \Rightarrow\ 10x = 100 \]
\[ \frac{10x}{10} = \frac{100}{10} \ \Rightarrow\ x = 10 \]
\[ 10\cdot10 - 15 = 100 - 15 = 85 \checkmark \]

Trying values of x in 10x − 15 = 85

x	10x − 15	Equals 85?
8	65	no
9	75	no
10	85	yes
11	95	no
12	105	no

Questions

What is x in 10x − 15 = 85?

The solution of 10x − 15 = 85 is x = 10.

How do you solve 10x − 15 = 85?

Add 15 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) − 15 = 85, which is 85.

Solve 10x − 15 = 85

How to work it out

Trying values of x in 10x − 15 = 85

Questions

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