Answer:
We know that Hattie purchased 12*a pounds of apples.
We also know that a is the cost per apple, and in one apple we have about 0.33 lb, then in a pound of apples we have N apples, such that:
N*0.33lb = 1lb
N = 1/0.33lb = 3
In a pound of apples, we have 3 apples, then in 12*a pounds of apples we have a total of:
12*a*3 apples.
each apple costs a, then the total cost in apples is:
(12*a)*(3*a)
36*a^2
We also know that she bought 4*b pounds of bananas, and each banana costs b.
We know that one banana weights around the same as an apple, then we also would have 3 bananas in one pound of bananas.
In 4*b pounds of bananas, we wil have:
4*b*3 bananas in total.
And each one costs b, then the price in bananas is:
4*b*3*b
12*b^2
The total cost is:
36*a^2 + 12*b^2
