Ineed the answer to 2a+b-a+3b it's in the maths section of my homework and i'm struggling to answer it

What is the slope of the line shown below?

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.

Find an bif a = {3, 6, 9, 12) and b = {2, 4, 6, 8, 10).