Solve 5x + 15 = −30

The solution of 5x + 15 = −30 is x = -9.

5x + 15 = -30\ \Rightarrow\ x = -9

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The lines y = 5x + 15 and y = -30 meet at x = -9. 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 addition, then the multiplication.
$5x + 15 = -30$
2
Subtract 15 from both sides:
$5x + 15 - 15 = -30 - 15 \ \Rightarrow\ 5x = -45$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{-45}{5} \ \Rightarrow\ x = -9$
4
Check: put x = -9 back into the equation.
$5\cdot(-9) + 15 = -45 + 15 = -30 \checkmark$

LaTeX source of the formulas on this page

\[ 5x + 15 = -30\ \Rightarrow\ x = -9 \]
\[ 5x + 15 = -30 \]
\[ 5x + 15 - 15 = -30 - 15 \ \Rightarrow\ 5x = -45 \]
\[ \frac{5x}{5} = \frac{-45}{5} \ \Rightarrow\ x = -9 \]
\[ 5\cdot(-9) + 15 = -45 + 15 = -30 \checkmark \]

Trying values of x in 5x + 15 = −30

x	5x + 15	Equals -30?
-11	-40	no
-10	-35	no
-9	-30	yes
-8	-25	no
-7	-20	no

Questions

What is x in 5x + 15 = −30?

The solution of 5x + 15 = −30 is x = -9.

How do you solve 5x + 15 = −30?

Subtract 15 from both sides to get 5x = -45, then divide both sides by 5 to get x = -9.

How do I check the answer?

Replace x by -9: 5(-9) + 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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