These two lines are graphs of non-proportional relationships what makes them not proportional

Choosing a booth location: your manager is sending two people to work at the conference. she wants a booth that will give your company good visibility for no more than 35% of the total budget ($3000). the conference coordinator just told you there are only five booths left. which booth will you choose? write the inequality that shows how much money you can spend on the booth simplify the inequality that shows how much money you can spend on the booth.

Twelve less than a number is at most 20

Find the domain and range of the following function f(x) = 51x - 21+ 4