The following figures are similar. They are both the same shape, One is just bigger.
The cost function is an illustration of a linear function
The equation of the cost function is C(x) = 35 + 0.5x
The given parameters are:
-- the cost of renting a cooler
--- the rate per bottle
Assume the number of bottles in a cooler is x.
The cost function for the bottles in a cooler would be:

So, we have:

Evaluate the products

Hence, the equation is 
Read more about linear functions at:
brainly.com/question/15602982
Y=mx+b
m=slope
b=y itnercept
remember the points go in (x,y) form
also, an easy way to find points is to subsitute values for x andn get values for y
so
6. y=5x-1
some points are (0,-1) (1,4) (2,9) (314)
7. y=-x+8
some points are (0,8) (1,7) (2,6) (3,5)
8. y=0.2x+.3
somepoints are (0,0.3) (1,0.5) (2,0.7) (3,0.9)
9. y=1.5x-3
somepoints are (0,-3) (1,-1.5) (2,0) (3,1.5)
10. y=-1/2x+4
somepoints are (0,4) (1,7/2) (2,3) (3,5/2)
11. y=2/3x-5
some points are (0,-5) (1,-13/3) (2,-11/3) (3,-3)
Red I know because the smaller the number the bigger the fraction