Question 4832
Set it up as a proportionality and cross multiply:
{{{15/100=x/13.50}}}
100x=15*13.5
100x=202.5
divide both sides by 100
x=$2.025, round to $2.03

Or think about $1.35 being 10% of $13.5, so 5% would be half of $1.35 ($.675)
15% is 10%+5% SO
15% = $1.35+$.675 = $2.025 round to $2.03