Hi,
Do not get bogged down by names. Rely on logic, since
maths is all about using that.
Look at 4ab - 8b:
1. Rewriting, we have (4b)(a) - 2(4b), so 4b is common in
both terms.
2. Then factor out 4b, that is, (4b)(a - 2).
Finally, we simplify, that is, (1/4)(4b)(a - 2)
= b(a - 2).
Thanks.
Cheers,
Wen Shih