(-2)-(-5)+(-9)-(-7)
=-2+5-9+7
=5+7-2-9
=1
(-32)-(-27)-(-72)-87
=-32+27+72-87
=27+72-32-87
=-20
0-(+9)-(-18)+(-9)
=0-9+18-9
=0+18-9-9
=0
(-2)-(-5)+(-9)-(-7)
=-2+5-9+7
=5+7-2-9
=1
(-32)-(-27)-(-72)-87
=-32+27+72-87
=27+72-32-87
=-20
0-(+9)-(-18)+(-9)
=0-9+18-9
=0+18-9-9
=0