b)-298+-300+-302
=(-298+-302)+-300
=-600+-300
=-900
a)248+-12+2064+-236
=248+(-12+-236)+2064
=0+2064
=2064
a, 248+(-12)+2064+(-236)
= [248+(-12)+(-236)]+2064
=0+2064
=2064
b, (-298)+(-300)+(-302)
=(-298)+(-300)+[-300+(-2)]
=[-298+(-2)]+[-300+(-300)]
=-300+(-300)
=-600