Answer:
the best way to solve this is to have graph paper, so your numbers and points align. I have a model attached. the first point is hours slept 8. so on your graph go to 8 then across to 83, which is the test score. make a mark to represent this point. do this for all and it will create a line
Y = 12x is a direct variation which is a proportion.
As x increases y also increases.
Let x is the amount of $11 per pound coffee
then the equation will be,
11x + 3(30) = 5 (x + 30)
11x + 90 = 5x + 150
11x - 5x = 150 - 90
6x = 60
x = 10
So, $10 is the amount of $11 per coffee that should be added