Solve 3x − 15 = −27

The solution of 3x − 15 = −27 is x = -4.

3x - 15 = -27\ \Rightarrow\ x = -4

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The lines y = 3x − 15 and y = -27 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.
$3x - 15 = -27$
2
Add 15 to both sides:
$3x - 15 + 15 = -27 + 15 \ \Rightarrow\ 3x = -12$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{-12}{3} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$3\cdot(-4) - 15 = -12 - 15 = -27 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 15 = -27\ \Rightarrow\ x = -4 \]
\[ 3x - 15 = -27 \]
\[ 3x - 15 + 15 = -27 + 15 \ \Rightarrow\ 3x = -12 \]
\[ \frac{3x}{3} = \frac{-12}{3} \ \Rightarrow\ x = -4 \]
\[ 3\cdot(-4) - 15 = -12 - 15 = -27 \checkmark \]

Trying values of x in 3x − 15 = −27

x	3x − 15	Equals -27?
-6	-33	no
-5	-30	no
-4	-27	yes
-3	-24	no
-2	-21	no

Questions

What is x in 3x − 15 = −27?

The solution of 3x − 15 = −27 is x = -4.

How do you solve 3x − 15 = −27?

Add 15 to both sides to get 3x = -12, then divide both sides by 3 to get x = -4.

How do I check the answer?

Replace x by -4: 3(-4) − 15 = -27, which is -27.

Solve 3x − 15 = −27

How to work it out

Trying values of x in 3x − 15 = −27

Questions

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