You ordered 2 drinks:
2 x 2.49 = 4.98
You ordered an entree: 12.95
Add the two numbers together
12.95 + 4.98 = 17.93
There is a 5% (or 0.05) sales tax
17.93 x 0.05 = 0.8965 (0.90 rounded)
Add the two together
17.9 + 0.90 = 18.80
$18.80 is your answer
hope this helps