(1)10 - 10 = (2)40 - 10 = (3)30 - 10 = (4)30 - 20 = (5)90 - 60 = (6)40 - 30 = (7)50 - 10 = (8)10 - 10 = (9)70 - 60 = (10)60 - 60 = (11)80 - 10 = (12)20 - 20 = (13)80 - 60 = (14)60 - 50 = (15)10 - 10 =