Question 153467
This is a bit fuzzy as problems go. Is the tip 20% of the original bill, or 20% of the bill after the tax?

Let's assume it is 20% of the original bill.

Then the total cost is given as $25.
The tax is 7.75% of the CostOfFood = {{{0.0775*CostOfFood}}}
The tip is 20% of the CostOfFood = {{{0.2*CostOfFood}}}
The total cost is 
{{{TotalCost = CostOfFood + Tax + Tip}}}
{{{25 = CostOfFood + 0.0775*CostOfFood + 0.2*CostOfFood}}}
{{{25 = 1.2775*CostOfFood}}}
{{{25/1.2775 = CostOfFood}}}
{{{19.57 = CostOfFood}}}