中2英文應用數學題+列式（十五點）

請幫幫忙！
題目如下：
I spend $68 in buying apples at 5 for $3 and oranges at 5 for $2. I sell three-fourths of my apples and four-fifths of my oranges for $57, making a profit of $5 on them. How many apples do i buy?

請列式，唔該。