Solve 10x − 2 = 78

The solution of 10x − 2 = 78 is x = 8.

10x - 2 = 78\ \Rightarrow\ x = 8

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The lines y = 10x − 2 and y = 78 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.
$10x - 2 = 78$
2
Add 2 to both sides:
$10x - 2 + 2 = 78 + 2 \ \Rightarrow\ 10x = 80$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{80}{10} \ \Rightarrow\ x = 8$
4
Check: put x = 8 back into the equation.
$10\cdot8 - 2 = 80 - 2 = 78 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 2 = 78\ \Rightarrow\ x = 8 \]
\[ 10x - 2 = 78 \]
\[ 10x - 2 + 2 = 78 + 2 \ \Rightarrow\ 10x = 80 \]
\[ \frac{10x}{10} = \frac{80}{10} \ \Rightarrow\ x = 8 \]
\[ 10\cdot8 - 2 = 80 - 2 = 78 \checkmark \]

Trying values of x in 10x − 2 = 78

x	10x − 2	Equals 78?
6	58	no
7	68	no
8	78	yes
9	88	no
10	98	no

Questions

What is x in 10x − 2 = 78?

The solution of 10x − 2 = 78 is x = 8.

How do you solve 10x − 2 = 78?

Add 2 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) − 2 = 78, which is 78.

Solve 10x − 2 = 78

How to work it out

Trying values of x in 10x − 2 = 78

Questions

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