Tania is NOT correct~
The amount of money she spent on apples is: 8a (cents)
The amount of money she spent on bananas is: 10b (cents)
The total amount of money she spent on apples and bananas is:
8a+ 10b (cents)
8a+ 10b
= 2(4a+ 5b) (distributive property)
Because 2(4a+ 5b) ≠ 18ab, she is not correct.
Hope this helps~