Answer:
Try to solve the similtanious equation to find the first term and the common difference, then use that information to figure out the 80th term... Update me if you need further help ...
Let's find the total cost before the tax and tip.
14+16+2*1.25+2*4.25 = $41
The tip is added before the tax so let's calculate it first.
1.15 * 41 = $47.15
Now add the 7% tax.
1.07 * 47.15 = $50.45
I am not sure about the linear equation format but I used
1,775,721 = 5.879x + 1.704x + x
to get an estimated population of
206,886.151
The answer to the question should be 4 candles and the first candle would not still be lit.