Solve 10x + 15 = −55

The solution of 10x + 15 = −55 is x = -7.

10x + 15 = -55\ \Rightarrow\ x = -7

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The lines y = 10x + 15 and y = -55 meet at x = -7. 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.
$10x + 15 = -55$
2
Subtract 15 from both sides:
$10x + 15 - 15 = -55 - 15 \ \Rightarrow\ 10x = -70$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{-70}{10} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$10\cdot(-7) + 15 = -70 + 15 = -55 \checkmark$

LaTeX source of the formulas on this page

\[ 10x + 15 = -55\ \Rightarrow\ x = -7 \]
\[ 10x + 15 = -55 \]
\[ 10x + 15 - 15 = -55 - 15 \ \Rightarrow\ 10x = -70 \]
\[ \frac{10x}{10} = \frac{-70}{10} \ \Rightarrow\ x = -7 \]
\[ 10\cdot(-7) + 15 = -70 + 15 = -55 \checkmark \]

Trying values of x in 10x + 15 = −55

x	10x + 15	Equals -55?
-9	-75	no
-8	-65	no
-7	-55	yes
-6	-45	no
-5	-35	no

Questions

What is x in 10x + 15 = −55?

The solution of 10x + 15 = −55 is x = -7.

How do you solve 10x + 15 = −55?

Subtract 15 from both sides to get 10x = -70, then divide both sides by 10 to get x = -7.

How do I check the answer?

Replace x by -7: 10(-7) + 15 = -55, which is -55.

Solve 10x + 15 = −55

How to work it out

Trying values of x in 10x + 15 = −55

Questions

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