Well, to find a percentage you take the percent and convert it to decimal form and then multiply that by your other number. For example:
15% of 150 = ?
15% = 0.15
0.15 x 150 = 22.5
So, 15% of 150 is 22.5
The problem you have takes the percent and adds it back to the original number. For example:
$25.75 + 15% = ?
15% = 0.15
0.15 x $25.75 = $3.86
$3.86 + $25.75 = $29.61
Does that make sense? ^_^
