Solve 10x − 8 = 42

The solution of 10x − 8 = 42 is x = 5.

10x - 8 = 42\ \Rightarrow\ x = 5

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The lines y = 10x − 8 and y = 42 meet at x = 5. 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.
$10x - 8 = 42$
2
Add 8 to both sides:
$10x - 8 + 8 = 42 + 8 \ \Rightarrow\ 10x = 50$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{50}{10} \ \Rightarrow\ x = 5$
4
Check: put x = 5 back into the equation.
$10\cdot5 - 8 = 50 - 8 = 42 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 8 = 42\ \Rightarrow\ x = 5 \]
\[ 10x - 8 = 42 \]
\[ 10x - 8 + 8 = 42 + 8 \ \Rightarrow\ 10x = 50 \]
\[ \frac{10x}{10} = \frac{50}{10} \ \Rightarrow\ x = 5 \]
\[ 10\cdot5 - 8 = 50 - 8 = 42 \checkmark \]

Trying values of x in 10x − 8 = 42

x	10x − 8	Equals 42?
3	22	no
4	32	no
5	42	yes
6	52	no
7	62	no

Questions

What is x in 10x − 8 = 42?

The solution of 10x − 8 = 42 is x = 5.

How do you solve 10x − 8 = 42?

Add 8 to both sides to get 10x = 50, then divide both sides by 10 to get x = 5.

How do I check the answer?

Replace x by 5: 10(5) − 8 = 42, which is 42.

Solve 10x − 8 = 42

How to work it out

Trying values of x in 10x − 8 = 42

Questions

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