Question 29775
Percentages can be done many ways.  First you need to know some vocabulary.
"of" means multiply
"%" means part of 100
"is" means equals
"what number" is usually represented by x or n
There is a siple formula that will work for all three types of problems you have stated here.
{{{ (is/of) = (percent/100) }}}
$15 is what % of $75
{{{ (15/75) = (x/100) }}}
cross multiply
{{{ (15 * 100) = (75x) }}}
divide both sides by 75
{{{ ((15)(100))/(75) = x }}}
now just multiply the numerator out and divide by the denomonator.
or reduce the fraction first, and then multiply and divide. as I did here.
{{{ (15)(4)/(3) = x }}}
{{{ 60/3 = x }}}
{{{ 20 = x }}}
and you are done.