Question

factor: zr-zf+cr-cf

Answer 1

if you see that more or more terms have something in common you can factor it out :)

so like zr - zf have a z in common right?

so you can factor out a z to become z(r-f)

Answer 2

you would then use the same idea for cr - cf which has a c in common

Answer 3

got t thanks :)

Answer 4

you're welcome :)