so assume19.5=100% the markup is 2 dollars 2=x% find x if 19.5=100%
so since they are proportionite 19.5:100 and 2:x if we make them fractions and flip one of them then multiply we will get 1 since 2/4=1/2 2/4 times 2/1=4/4=1 so
19.5/100 times x/2=19.5x/200=1 19.5x/200=1 multiply both sides by 200 19.5x=200 divide both sdies by 19.5 x=10.256 aprox x=10.3% markup