Answer:
Assuming a pre-tax bill of $150 with a 7% tax and a 20% tip, the total amount is $150 + ($150 * 0.07) + ($150 * 0.20) = $187.50. To split the bill evenly among 10 people, each person should pay $187.50 / 10 = $18.75. If you did not pay the full bill, send $18.75 to the person who did.