42-56+33-(33-56+42)
=42-56+33-33+56-42
=0
54-(45-30+54)-30+5
=54-45+30-54-30+5
=-40
42-56+33-(33-56+42)= 42-56+33-33+56-42
= (42-42)-(56-56)+(33-33)
= 0
54-(45-30+54)-30+5= 54-45+30-54-30+5
= (54-54)-(45-5)+(30-30)
= 0-40+0= -40
42-56+33 - (33-56+42) = 42 - 56 +33 -33 - (-56 ) -42
= 42 - 56 +33 -33 +56 - 42
= (42 - 42) + (-56 + 56) + (33-33)
= 0 + 0 +0 =0
54 - (45-30+54) - 30+5 = 54- 45 -(-30 )- 54 -30+5
= 54 - 45 +30 -54 -30 + 5
= (54 - 54 ) +(30 - 30) -(40 +5 ) +5
= 0 + 0 -40 - 5 + 5
= -40 +(-5 +5 )
= -40 + 0 = -40