Solve 4x − 15 = 5

The solution of 4x − 15 = 5 is x = 5.

4x - 15 = 5\ \Rightarrow\ x = 5

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The lines y = 4x − 15 and y = 5 meet at x = 5. 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.
$4x - 15 = 5$
2
Add 15 to both sides:
$4x - 15 + 15 = 5 + 15 \ \Rightarrow\ 4x = 20$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{20}{4} \ \Rightarrow\ x = 5$
4
Check: put x = 5 back into the equation.
$4\cdot5 - 15 = 20 - 15 = 5 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 15 = 5\ \Rightarrow\ x = 5 \]
\[ 4x - 15 = 5 \]
\[ 4x - 15 + 15 = 5 + 15 \ \Rightarrow\ 4x = 20 \]
\[ \frac{4x}{4} = \frac{20}{4} \ \Rightarrow\ x = 5 \]
\[ 4\cdot5 - 15 = 20 - 15 = 5 \checkmark \]

Trying values of x in 4x − 15 = 5

x	4x − 15	Equals 5?
3	-3	no
4	1	no
5	5	yes
6	9	no
7	13	no

Questions

What is x in 4x − 15 = 5?

The solution of 4x − 15 = 5 is x = 5.

How do you solve 4x − 15 = 5?

Add 15 to both sides to get 4x = 20, then divide both sides by 4 to get x = 5.

How do I check the answer?

Replace x by 5: 4(5) − 15 = 5, which is 5.

Solve 4x − 15 = 5

How to work it out

Trying values of x in 4x − 15 = 5

Questions

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