Answer:
Answer is explained in the explanation section below.
Step-by-step explanation:
Function given:
u(x,y) = min(3x,y)
Where, x = cups of coffee
y = containers of creamer.
From the above equation, we know that:
3x = y
For a week, Harry consumes 7 cups of coffee with 21 containers of creamers.
Thus,
u(x,y) = min (3x,y)
u(x,y) = min (3x7,21)
u(x,y) = min (21,21)
u(x,y) = 21
Now, if Harry 21 containers, he will get 28 (21 +7)
Thus,
u(x,y) = min(3x,y)
u(x,y) = min(3x7,28)
u(x,y) = min(21,28)
u(x,y) = 21
Additional 7 containers are useless cup of coffee and 3 containers of creamer are used together. Thus, for 7 cups of coffee Harry only needs 21 containers of creamer.