# How do you solve 1.2x + 1 = 9?

Jul 9, 2015

Process shown below

#### Explanation:

$1.2 x + 1 = 9$

Add $\text{ -1}$ on both sides

$1.2 x + 1 - 1 = 9 - 1$

$1.2 x + 0 = 8$

$1.2 x = 8$

$\frac{12}{10} x = 8$

multiply 10 on both sides

$\frac{12 x}{10} \times 10 = 8 \times 10$

$12 x = 80$

divide with 12 on both sides

$\left(12 x\right) \times \frac{1}{12} = \frac{80}{12}$

$x = \frac{80}{12}$

$x = \frac{20}{3}$

Jul 9, 2015

$x = 6.666 \ldots$

#### Explanation:

Here x is the unknown variable, whose value is to be found. We take the '1' to the right hand side [You can also think of subtracting both sides by 1 - it's the same thing here], so the equation becomes,

$1.2 \cdot x = 9 - 1 = 8$

Now taking the $1.2$ to the right hand side [You can think of dividing both sides by $1.2$ ], we get:

$x = \frac{8}{1.2} = 6.66 \ldots$ which is 6.67 when rounded off to two decimal places.

Note: if you need the answer in the form of a fraction, then in the last step where $x = \frac{8}{1.2}$, multiply the numerator and the denominator by 10 [so that you get rid of the decimal point] and simplify to the simplest form by dividing the numerator and denominator by 4. Then, $x = \frac{8 \cdot 10}{1.2 \cdot 10} = \frac{80}{12} = \frac{\frac{80}{4}}{\frac{12}{4}} = \frac{20}{3}$