1,- ( 81 - 32 - 47 ) + 81 - ( 32 + 2 )
= -81 + 32 + 47 + 81 - 32 - 2
= ( 81 - 81 ) + ( 32 - 32 ) + ( 47 - 2 )
= 0 + 0 + 45
= 45
2, 50 - ( 47 + 50 - 18 ) + ( 47 - 18 )
= 50 - 47 - 50 + 18 + 47 - 18
= ( 50 - 50 ) + ( 47 - 47 ) + ( 18 - 18 )
= 0 + 0 + 0
= 0
3,- ( 15 - 47 + 58 ) + ( 15 - 47 ) + 3
= -15 + 47 - 58 + 15 - 47 + 3
= ( 15 - 15 ) + ( 47 - 47 ) + ( 3 - 58 )
= 0 + 0 + ( -55 )
= -55