Solve 2x − 15 = 25

The solution of 2x − 15 = 25 is x = 20.

2x - 15 = 25\ \Rightarrow\ x = 20

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The lines y = 2x − 15 and y = 25 meet at x = 20. 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.
$2x - 15 = 25$
2
Add 15 to both sides:
$2x - 15 + 15 = 25 + 15 \ \Rightarrow\ 2x = 40$
3
Divide both sides by 2:
$\frac{2x}{2} = \frac{40}{2} \ \Rightarrow\ x = 20$
4
Check: put x = 20 back into the equation.
$2\cdot20 - 15 = 40 - 15 = 25 \checkmark$

LaTeX source of the formulas on this page

\[ 2x - 15 = 25\ \Rightarrow\ x = 20 \]
\[ 2x - 15 = 25 \]
\[ 2x - 15 + 15 = 25 + 15 \ \Rightarrow\ 2x = 40 \]
\[ \frac{2x}{2} = \frac{40}{2} \ \Rightarrow\ x = 20 \]
\[ 2\cdot20 - 15 = 40 - 15 = 25 \checkmark \]

Trying values of x in 2x − 15 = 25

x	2x − 15	Equals 25?
18	21	no
19	23	no
20	25	yes
21	27	no
22	29	no

Questions

What is x in 2x − 15 = 25?

The solution of 2x − 15 = 25 is x = 20.

How do you solve 2x − 15 = 25?

Add 15 to both sides to get 2x = 40, then divide both sides by 2 to get x = 20.

How do I check the answer?

Replace x by 20: 2(20) − 15 = 25, which is 25.

Solve 2x − 15 = 25

How to work it out

Trying values of x in 2x − 15 = 25

Questions

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