54 - ( 45 - 30 + 54 ) - 30 + 5
= 54 - 45 + 30 - 54 - 30 + 5
= ( 54 - 54 ) - ( 45 - 5 ) + ( 30 - 30 )
= 0 - 40 + 0
= - 40
= 54-45+30-54-30+5
= (54-54) + (30-30) - (45-5)
= -40
\(\text{54-(45-30+54)-30+5}\)
\(=54-45+30-54-30+5\)
\(=9+30-54-30+5\)
\(=39-54-30+5\)
\(=-15-30+5\)
\(=-45+5\)
\(=-40\)