One idea is:
Paul wants to buy an iphone X. He has savings of $100 to start with. Local McDonalds pays $7 per hour (after tax) to students on summer break for helping out at the counter. The iphone costs $1000. At least how many hours does Paul need to work at McDonalds to be able to afford the iphone.
So, that matches ax+b>c in that
a is the hourly earning
b is the initial savings
c is the price of the iphone
I honestly don'y know i'm really sorry.
Yes, the line passes the vertical line test (no x-values are repeated)
60 miles an hr.. Because 180 divides by three is 60 and that is the answer per hr
$8.58 will be your answer