Solve 10x − 15 = 105

The solution of 10x − 15 = 105 is x = 12.

10x - 15 = 105\ \Rightarrow\ x = 12

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The lines y = 10x − 15 and y = 105 meet at x = 12. 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.
$10x - 15 = 105$
2
Add 15 to both sides:
$10x - 15 + 15 = 105 + 15 \ \Rightarrow\ 10x = 120$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{120}{10} \ \Rightarrow\ x = 12$
4
Check: put x = 12 back into the equation.
$10\cdot12 - 15 = 120 - 15 = 105 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 15 = 105\ \Rightarrow\ x = 12 \]
\[ 10x - 15 = 105 \]
\[ 10x - 15 + 15 = 105 + 15 \ \Rightarrow\ 10x = 120 \]
\[ \frac{10x}{10} = \frac{120}{10} \ \Rightarrow\ x = 12 \]
\[ 10\cdot12 - 15 = 120 - 15 = 105 \checkmark \]

Trying values of x in 10x − 15 = 105

x	10x − 15	Equals 105?
10	85	no
11	95	no
12	105	yes
13	115	no
14	125	no

Questions

What is x in 10x − 15 = 105?

The solution of 10x − 15 = 105 is x = 12.

How do you solve 10x − 15 = 105?

Add 15 to both sides to get 10x = 120, then divide both sides by 10 to get x = 12.

How do I check the answer?

Replace x by 12: 10(12) − 15 = 105, which is 105.

Solve 10x − 15 = 105

How to work it out

Trying values of x in 10x − 15 = 105

Questions

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