# How do you solve \frac { x } { 900} = \frac { 35} { 15}?

Dec 1, 2017

$x = 2100$

#### Explanation:

First cross multiply to have a linear equation:

$15 x = 900 \cdot 35$
$15 x = 31500$

To isolate $x$, divide by 15:

$x = \frac{31500}{15}$

$x = 2100$

Dec 1, 2017

The easiest way to do this is to cross multiply and set the equation up like

$15 x = 900 \cdot 35$

#### Explanation:

Think of it like you're multiplying $15$ to both sides, which gets rid of the fraction on the right side (because $\frac{15}{15} = 1$). This also works for the left side when you multiply each side by $900$.

After you get

$15 x = 31500$

simplify it by dividing each side by $15$ to get

$x = 2100$

Dec 2, 2017

$x = 2100$

#### Explanation:

In $\text{ "x/900 = 35/15" }$ you need to isolate $x$

Multiply both sides by $900$ to cancel the fraction with $x$

$\frac{\textcolor{b l u e}{900 \times} x}{900} = \frac{\textcolor{b l u e}{900 \times} 35}{15}$

$\frac{\cancel{900} \times x}{\cancel{900}} = \frac{{\cancel{900}}^{60} \times 35}{\cancel{15}} \text{ } \leftarrow$ simplify

$x = 2100$

In this case I would not use cross-multiplying because it changes a $1 x$ term into a $15 x$ term, which then has to be divided by $15$