Javier and his friends go out to eat. the restaurant they chose automatically adds a 15% gratuity to their food bill since they are a party of 12. the total bill after the automatic 15% gratuity was $213.90. because they received such good service, the group decided to add an extra $20 to the total bill as an additional tip. so, instead of leaving a 15% tip, javier and his friends ended up leaving a tip that was about ( ) % of the food bill.

well, we know that 213.90 includes the 15% gratuity, so if the meal price was say "x", namely that is the 100%, and we add 15% to that, then 100% + 15% = 115%, so 213.90 is really the 115%.

now, if 213.90 is the 115.%, what is "x"?  the 100%.

so since we know the meal without the tip is 186 bucks, the tip was then 213.90 - 186 = 27.90.

but they got extra potato wedges with butter and the waitress was wearing her best hat, they added $20 more, so the tip ended  up as 27.90 + 20 = 47.90.

now, if the cost of the meal was $186 and that is the 100%, what is 47.90 off of it in percentage?