Tina has 3 stacks of 5cds on each of 3 shelves. how nany cds does she have

So this problem written out should look like this: 
3(3 x 5)
Firstly, to simplify this we should multiply 3 x 5. That is 15.
3(15)      This is equal to 3 x15, so that is exactly what we must do.
3 x 15 is equal to 45. Tina has 45 CDs in total.
Hope this helps!