Answer :

iGreen
You cross multiply and solve for the unknown variable.

Here's an example:

[tex]\sf\dfrac{2}{3}=\dfrac{6}{x}[/tex]

Cross multiply:

[tex]\sf3\times6=2\times~x[/tex]

[tex]\sf18=2x[/tex]

Divide 2 to both sides:

[tex]\sf~x=9[/tex]
siahsavage
One way is to cross multiply and then solve from there.
Example:

10/x = 2/5
(10*5 = 2*x)
50 = 2x
(50/2)
25 = x

10/25 = 2/5