Which graph shows a function whose inverse is also a function?

Can someone me do math because i am having a breakdown rn because i don’t get it

1. find the area of the unshaded square 2. find the area of the large square 3. what is the area of the frame represented by the shaded region show

Tom is the deli manager at a grocery store. he needs to schedule employee to staff the deli department for no more that 260 person-hours per week. tom has one part-time employee who works 20 person-hours per week. each full-time employee works 40 person-hours per week. write and inequality to determine n, the number of full-time employees tom may schedule, so that his employees work on more than 260 person-hours per week. graph the solution set to this inequality.