math 1:
suppose that the function f(x) = 2x + 12 represents the cost to rent x video games a month from an internet gaming club. george now has $4. how many more dollars does george need to rent 13 video games next month?

We know x= the # of video games rented a month. George wants to rent 13 video games next month. We set x=13. This gives us the equation

This gives us 
38 dollars is how much 13 video games cost for a month. George already has 4 dollars. We do 
George needs to get $34 rent out 13 video games the next month.