Solve 5x − 5 = 15

The solution of 5x − 5 = 15 is x = 4.

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

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The lines y = 5x − 5 and y = 15 meet at x = 4. 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.
$5x - 5 = 15$
2
Add 5 to both sides:
$5x - 5 + 5 = 15 + 5 \ \Rightarrow\ 5x = 20$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{20}{5} \ \Rightarrow\ x = 4$
4
Check: put x = 4 back into the equation.
$5\cdot4 - 5 = 20 - 5 = 15 \checkmark$

LaTeX source of the formulas on this page

\[ 5x - 5 = 15\ \Rightarrow\ x = 4 \]
\[ 5x - 5 = 15 \]
\[ 5x - 5 + 5 = 15 + 5 \ \Rightarrow\ 5x = 20 \]
\[ \frac{5x}{5} = \frac{20}{5} \ \Rightarrow\ x = 4 \]
\[ 5\cdot4 - 5 = 20 - 5 = 15 \checkmark \]

Trying values of x in 5x − 5 = 15

x	5x − 5	Equals 15?
2	5	no
3	10	no
4	15	yes
5	20	no
6	25	no

Questions

What is x in 5x − 5 = 15?

The solution of 5x − 5 = 15 is x = 4.

How do you solve 5x − 5 = 15?

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

How do I check the answer?

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

Solve 5x − 5 = 15

How to work it out

Trying values of x in 5x − 5 = 15

Questions

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