The area of D is given by:

The average value of f over D is given by:
Answer:
$10
Step-by-step explanation:
Since 6 cost four dollars 3 would cost 2 dollars multiply 3 to get 15 bananas and 2 to get $10
(2y-9)(2y-9)
(2y-9)^2
(2y)^2-2*2y*9+9^2
4y^2-36y+81