Solve 10x − 7 = −87

The solution of 10x − 7 = −87 is x = -8.

10x - 7 = -87\ \Rightarrow\ x = -8

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The lines y = 10x − 7 and y = -87 meet at x = -8. 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.
$10x - 7 = -87$
2
Add 7 to both sides:
$10x - 7 + 7 = -87 + 7 \ \Rightarrow\ 10x = -80$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{-80}{10} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$10\cdot(-8) - 7 = -80 - 7 = -87 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 7 = -87\ \Rightarrow\ x = -8 \]
\[ 10x - 7 = -87 \]
\[ 10x - 7 + 7 = -87 + 7 \ \Rightarrow\ 10x = -80 \]
\[ \frac{10x}{10} = \frac{-80}{10} \ \Rightarrow\ x = -8 \]
\[ 10\cdot(-8) - 7 = -80 - 7 = -87 \checkmark \]

Trying values of x in 10x − 7 = −87

x	10x − 7	Equals -87?
-10	-107	no
-9	-97	no
-8	-87	yes
-7	-77	no
-6	-67	no

Questions

What is x in 10x − 7 = −87?

The solution of 10x − 7 = −87 is x = -8.

How do you solve 10x − 7 = −87?

Add 7 to both sides to get 10x = -80, then divide both sides by 10 to get x = -8.

How do I check the answer?

Replace x by -8: 10(-8) − 7 = -87, which is -87.

Solve 10x − 7 = −87

How to work it out

Trying values of x in 10x − 7 = −87

Questions

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