Michael pays $30 to enter a state fair, plus $4 for each ride. which of the following equations represents his total cost?

$30 is the amount Michael pays when he goes inside (it does not change), so it is + 30

Michael pays $4 per ride, which means that it needs a variable, for you do not know how much rides Michael is going on.

y = total
x = amount of rides

so your equation is:

y = 4x + 30, or D

hope this helps