Solve 7x + 15 = −55

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

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

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

LaTeX source of the formulas on this page

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

Trying values of x in 7x + 15 = −55

x	7x + 15	Equals -55?
-12	-69	no
-11	-62	no
-10	-55	yes
-9	-48	no
-8	-41	no

Questions

What is x in 7x + 15 = −55?

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

How do you solve 7x + 15 = −55?

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

How do I check the answer?

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

Solve 7x + 15 = −55

How to work it out

Trying values of x in 7x + 15 = −55

Questions

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