If you want to solve [tex]\dfrac{a}{b} = c[/tex] for [tex]b[/tex], start by getting rid of the fraction.
Multiply both sides of the equation by [tex]b[/tex].
[tex]b\cdot \dfrac{a}{b} = b\cdot c[/tex]
This will get rid of the fraction on the left and give you
[tex]a = b\cdot c[/tex]
Now this is a regular old equation without fractions. To get [tex]b[/tex] by itself, you need to divide away [tex]c[/tex] from both sides of the equation.
Can you finish it from there?
