Hi Ed,

What you charge your customer is made up of two pieces, $10.95 which is your cost and the remainder which is your margin. By saying your margin is 19% what is meant is that your margin is 19% of what you charge your customer. This means that your cost must be 100% - 19% = 81% of what you charge your customer. To say this again

$10.95 is 81% of what you charge.

Thus if you charge $x then

$10.95 is 81% of $x or
$10.95 = 0.81 $x

Dividing both sides by 0.81 gives

$x = $10.95/0.81 = $13.52

Penny