Frank and 3 of his friends ate dinner at a restaurant. The bill came to $98.75 before tax. The tax rate is 6.5% and they decided to leave 20% tip. If they share the bill equally, how much will each person pay?

Either $41.64 per person or $42.07, depending on if they tip pre or post sales tax.

Step-by-step explanation:

b=98.75

x=6.5/100=0.065

p=20/100=0.2

If tipping on taxed subtotal:

T=[ (bx+b) p + (bx+b) ]/3

T=[ (98.75 (0.065) + 98.75) (0.2) + 98.75 (0.065) + 98.75]/3

T=42.07 per person

If tipping on untaxed subtotal:

T = (bx+bp+b) / 3

T = (98.75 (0.065) + 98.75 (0.2) + 98.75) / 3

T=41.64 per person