Answer :
.25x = 13.65
.75x = 13.65
x = 18.20
original bill was $18.20
3/18.20 = .165
165*100 = 16.5
16.5% tip
.75x = 13.65
x = 18.20
original bill was $18.20
3/18.20 = .165
165*100 = 16.5
16.5% tip