Answer:
Jill went for dinner
Let the total cost of the dinner = b
He gave 15% tip, then 15%(b) =0.15b
Total cost of the bill = b+0.15b = 1.15b = b
Percentage increase =
![(increased bill-original amount of bill)/(original amount of bill)](https://img.qammunity.org/2020/formulas/mathematics/high-school/v5ndqhgvc1y0oqvwepi4kxncz8qgmos0q0.png)
= 15%
The cost of the dinner is increased by 15% as he gave the bill.
Therefore, increase of 15% is the same as the percentage of bill.