Which situation can be modeled by a function?

Maria can spend $15 on 1 shirt, $15 on 2 shirts, or $30 on 3 shirts.
Bonnie can spend $10 on a shirt, $20 on 2 shirts, and $20 on 3 shirts.
Raquel can spend $15 on 1 shirt, $30 on 2 shirts, or $30 on 3 shirts.
Natalie can spend $15 on 1 shirt, $30 on 2 shirts, or $45 on 3 shirts.

Phyllis and chen are saving money to go to a football game. each friend starts with some money and saves a specific amount each week. phyllis made a graph to show the total she has saved at the end of each week. chen wrote an equation to show the total, y, he has saved at the end of each week, x. y = 15x + 15 compare the amount that each friend has when both friends start saving. select the correct answer from the drop-down menu to complete the statement. phyllis starts with $ and chen starts with $

Segment xy is dilated through point m with a scale factor of 2. which segment shows the correct result of the dilation

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=