How do you solve for the unknown variable in a proportion?

A proportion is an equation that states that two ratios are equal. It is written in the form:

a/b = c/d

where b and d are not equal to zero. To solve for the unknown variable, you can use cross-multiplication, which is a method that involves multiplying the numerator of one ratio by the denominator of the other ratio.

For example, if you have the proportion:

3/4 = x/8

To solve for x, you can cross-multiply:

3 x 8 = 4 x x

Simplifying the left side:

24 = 4x

And then solving for x:

x = 6

Therefore, the unknown variable, x, is equal to 6.