# How do you solve (3a)/4=36/12?

Mar 22, 2018

#### Explanation:

We can start by using cross multiplication. That is when we multiply the numerator of the one side with the denominator of the other side. This done with both numerators and denominators of the fractions. We then set the two products equal to each other.

$3 a \left(12\right) = 36 \left(4\right)$

Then simplifying on both sides.
$12 \cdot 3 = 36$ and $36 \cdot 4 = 144$
Therefore,

$36 a = 144$

Since we are saying (36) times (a), we can apply inverse operations to solve for a. The inverse of multiplication is division. So we divide by 36 on both sides.

$\frac{36 a}{36} = \frac{144}{36}$

Therefore $a = 4$

Hope this helps.

Mar 22, 2018

$a = 4$

#### Explanation:

$\frac{3 a}{4} = \frac{36}{12}$

Start by doing cross multiply

$\left(3 a\right) \left(12\right) = \left(36\right) \left(4\right)$

$36 a = 144$

Divide both sides by $36$

$\frac{\cancel{36} a}{\cancel{36}} = \frac{144}{36}$

$a = 4$