Agas station sells a coffee mug filled with coffee for $3. for each refill, using the same mug, the gas station charges $1.25 for the coffee. if y represents the total cost and x represents the total number of filled coffee mugs purchased, which function rule describes this pattern?

Since the price of the coffee itself is $1.25, the gradient of the function will be 1.25 and will give a straight line. However, since the first cup of coffee costs $3, when extrapolated to x = 0, the price is 3 - 1.25 = $1.75 which indicates the cost of using the cup. Therefore this is the y-intercept. This can be expressed as a linear function of y = mx + c where y is the price, m is the gradient, x is the number of times the cup has been filled with coffee, and c is the price of using the cup, giving:
y = 1.25x + 1.75

In all honesty, there really is no “work” per say to show. mainly it’s just using the process of elimination. the question is asking which domain(s) would be the most appropriate for the function c(n). n is the number of observed vehicles so right away, 1, 2, and 3 can be eliminated.why? 1, 2 start in the negatives and therefore it is impossible to observe negative cars. so, #4 would be the best answer to the given problem.