Answer:
D
Explanation:
you have to make groupes.
start with a² part and forget the rest from example.
-4a²-a²=? Now remember - and - is adding up. so -5a², which takes out options a and b, as there are 3a² instead of 5.
now let's take ab part and forge the rest.
-2ab+6ab=? that gives us 4ab. So option c, which says 8ab, is wrong. the last number isn't really important in this case because you've already seen the rest can't be.
