Answer :
Answer:
[tex] r(x) = 20 -1.29 x[/tex]
Step-by-step explanation:
Let's define some notation first:
[tex] x[/tex] represent the number of grapges that we buy
[tex] A= 20[/tex] represent the amount of money that we have in order to pay
[tex] C= 1.29[/tex] represent the unitary cost per each pound of grapes. This value sia assumed because is not logic that a pound of grapes cost $41.29.
[tex] r[/tex] represent the change
Solution to the problem
In order to find a function to the change we need to satisfy the following equation:
[tex] r+ Cx =A[/tex]
Because the change plus the ocost needs to be equal to the total amount.
If we solve for the change r we got this function:
[tex] r = A- Cx[/tex]
And if we replace the values for A and C we got:
[tex] r(x) = 20 -1.29 x[/tex]
And this would be our function for the change based on the info provided.