How to join SQL statements with different where clause on same column of same table

I have 2 statements in sqlite

1st Statement:

Select SUM(GrossQty) As GQTY, SUM(NetQty) As NQTY
  From NSales 
  Where IMonth=5 And IYear=2012 And IDay>15

Result:

GQty  NQty
 30    25

2nd Statement

Select SUM(GrossQty) As GQTY, SUM(NetQty) As NQTY
  From NSales 
  Where IMonth=6 And IYear=2012 And IDay<10

2nd Result:

GQty  NQty
 20    15

How can I combine these statements so that I get both these results added together like this?

Desired Result:

GQty  NQty
 50    40