Respuesta :

18.50/100 = 0.1850
0.1850 x 20 = 3.70
18.50 - 3.70 = 14.80

14.80/100 = 0.1480
0.1480 x 6 = 0.888
14.80 + 0.88 = 15.68

the final cost would be $15.68