# How do you use cross products to solve s/11=30/110?

Apr 4, 2017

Cross multiply to get $s = 3$

#### Explanation:

We can use the cross multiplication formula.
Following the image's suggestions, we can plug in $s$ for $a$, $11$ for $b$, $30$ for $c$, and $110$ for $d$.

We'd multiply $a$ and $d$, and $b$ and $c$.

$a \cdot d = s \cdot 110$ and $b \cdot c = 11 \cdot 30$.

$s \cdot 110 = 110 s$, and $11 \cdot 30 = 330$.

We'd then set the two values equal to each other: $110 s = 330$. We'd want to get $s$ to its simplest form, so divide both sides by $110$.

$\frac{110 s}{110} = s$, and $\frac{330}{110} = 3$, so $s = 3$.