Question 15124
You can solve proportions by cross-multiplying.

{{{65/10 = 13/x}}} Cross-multiply. This means, multiply both sides by x then multiply both sides by 10.

{{{65x = 10(13)}}} Simplify.
{{{65x = 130}}} Divide both sides by 65
{{{x = 2}}}


I assume that there is a typo in the second problem and you really meant to type:

{{{3/8 = 12/x}}} Try this yourself.  Cross-multiply, first by x then by 8, then you can solve for x.