5 small milkshake outcomes
5 medium milkshake outcomes
and
5 large milkshake outcomes
since there are only 5 flavors you can only make 5 different milkshakes unless you want to mix the flavors to make
5+10= 15 so you could make 15 that mixing each ice cream with each other and then mixing all of them.
I have attached the graph of y = -x + 1.5
The line goes through the points (0,1.5) and (1.5,0)
It increased by $3.15
The new monthly cost is $48.15
The slope is:(9-3)/(1-(-2))=6/3=2