Answer:
y=100x+75. Where y equals total cost and x equals numbers of weeks enrolled.
Explanation:
75 is the upfront cost, aka the cost of zero weeks, this cost will never change and is a one-time payment, therefore it needs no variable. 100 is the cost per week which means every week costs 100 more dollars, this is why it must have a variable because it will change with time. They are added together because they both show the total cost and together will show how much one person is spending.