=(-259+259)+[(-74)+(-26)]+(-81+581)
=0+(-100)+500
=400
= -259 + 259 - 74 - 26 + 581 + 259 - 81
= 0 - 100 + 840 - 81
= 659
-259+(-74)+581+259+(-260+(-81)
=(-259+259)+(-81+581)+[(-74)+(-26)]
=0+500+(-100)
=400
-259+(-74)+581+259+(-26)+(-81)
=(-259+259)+[(-74)+(-26)]+[581+(-81)]
=0+(-100)+500
=400