Given that
A full album cost $11
singles cost $2
A total of 100 albums were sold
Case 1: if 50 albums and 50 singles were sold
Then
The total revenue made will be
50 x $11 + 50 x $ 2
=> $ 550 + $100
=> $650
Case 2: If 51 albums and 49 singles were sold
Then
The total revenue made will be
51 x $11 + 49 x $2
=>$561 + $98
=>$659
Case 3: If 52 albums and 48 singles were sold
Then
The total revenue made will be
52 x $11 + 48 x $2
=>$572 + $96
=>$668
We can observe from the above that jTunes could make above $665 if more than 52 albums and 48 singles were sold.