Jawabanmu

2014-08-21T21:34:45+07:00
[5+(-8)-(-2)] - [-3+6+(-21)]
[5+(-6)] -[-3+(-15)]
(-1)-(-18)
-1+18 = 17
2014-08-21T21:38:05+07:00
[5+(-8)-(-2)] - [3-6+21]
-5              - 18
=13
hasilnya adanya
a -5
b -2
c -1
d 0
ka gimana ni tolong ka