Solve 5x − 15 = −30

The solution of 5x − 15 = −30 is x = -3.

5x - 15 = -30\ \Rightarrow\ x = -3

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The lines y = 5x − 15 and y = -30 meet at x = -3. 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.
$5x - 15 = -30$
2
Add 15 to both sides:
$5x - 15 + 15 = -30 + 15 \ \Rightarrow\ 5x = -15$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{-15}{5} \ \Rightarrow\ x = -3$
4
Check: put x = -3 back into the equation.
$5\cdot(-3) - 15 = -15 - 15 = -30 \checkmark$

LaTeX source of the formulas on this page

\[ 5x - 15 = -30\ \Rightarrow\ x = -3 \]
\[ 5x - 15 = -30 \]
\[ 5x - 15 + 15 = -30 + 15 \ \Rightarrow\ 5x = -15 \]
\[ \frac{5x}{5} = \frac{-15}{5} \ \Rightarrow\ x = -3 \]
\[ 5\cdot(-3) - 15 = -15 - 15 = -30 \checkmark \]

Trying values of x in 5x − 15 = −30

x	5x − 15	Equals -30?
-5	-40	no
-4	-35	no
-3	-30	yes
-2	-25	no
-1	-20	no

Questions

What is x in 5x − 15 = −30?

The solution of 5x − 15 = −30 is x = -3.

How do you solve 5x − 15 = −30?

Add 15 to both sides to get 5x = -15, then divide both sides by 5 to get x = -3.

How do I check the answer?

Replace x by -3: 5(-3) − 15 = -30, which is -30.

Solve 5x − 15 = −30

How to work it out

Trying values of x in 5x − 15 = −30

Questions

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