Answer :
Add 15% to the bill and then divide by 3.
they will pay (115% of $24.60) / 3
= (1.15 x 24.60) / 3
= $28.29 / 3
= $9.43
they will pay (115% of $24.60) / 3
= (1.15 x 24.60) / 3
= $28.29 / 3
= $9.43