Scenario 1
It is given that on Albert's favorite shoe website, the prices for a pair of the shoes range from $80 to $180 and the delivery fee is one-twentieth of the price of the basketball shoes.
We know that Albert has $105 to spend on new basketball shoes.
From the above pieces of information we see that the minimum that Albert will have to spend is [tex] 80+\frac{1}{12}\times 80=80+6.67=86.67 [/tex] dollars.
Now, we know that Albert can spend a maximum of $105 including the delivery fee. Let the upper limit of the price of the shoe Albert can buy be [tex] x [/tex]. So, the upper limit of the domain can be found as:
[tex] x+\frac{1}{12}x=105 [/tex]
[tex] \frac{13}{12}x=105[/tex]
[tex] \therefore x=\frac{105\times 12}{13}\approx 96.92[/tex] dollars.
Thus, in the first scenario, the domain of the total cost function, f(c) will be [86.67,96.92].
Scenario 2
After receiving $42 from his friend, Albert's total buying power becomes $147. Albert can now buy a costlier pair of shoes.
Thus, the maximum that Albert can buy is again given by:
[tex] x+\frac{1}{12}x=147[/tex]
Solving this we get: [tex] x=135.69[/tex] dollars
The lower limit will remain the same as the lowest price point in the website is $80. Therefore, in the second scenario the domain is:
[86.67, 135.69]