Step-by-step explanation:
Given function is,
Where,
y = amount paid to the gym in dollars
x = number of months
So when x = 0, y =55(0)+80 = 80
i.e when number of months is 0, you have to pay a fee of $80.
This is the one time fee to open a membership.
After that for each month you have to pay $55 for each months.
So 55 is multiplied with x.