Part a is incorrect because the fruit numbers aren't changed to one. You're showing the price correctly, but the amount of fruit is wrong.
For Part B, just write this:
Ten pounds of oranges will cost $0.60 more than ten pounds of bananas. Because the unit rate for oranges is $0.45 per pound, and the unit rate for bananas is $0.39 per pound. Ten pounds of oranges cost $4.50. For ten pounds of bananas, it cost $3.90.