The fixed cost for suit is $125 and for every additional day, the cost can be calculated as 30*x.
Therefore, the total cost is the sum of the fixed cost ($125) and the additional cost per additional day ($30x). So, the total cost y is:
y = 125 + 30x
To calculate the total cost after 3 days, we need to replace x by 3 on the initial equation as:
y = 125 + 30*3
y = 125 + 90
y = 215
Answers: 21. y = 125 + 30x
22. $215