Mark works at a popular electronics retail store. He earns a fixed income of $18 an hour and a 5% commission on the sales he makes.
Let's say,
y = earnings
h = number of hours worked
s = amount of sales
Which of these equations correctly indicates how much Mark earns in a day?
A : y=18h+0.5s
B : y=18h+0.05s
C : y=h/18+5s
D : y=h/18+s/5