Question

Can someone help me on number one plz. Help me by explaining the steps ;D

Answer 1

It's easy since all the variables have a after them they can be added and subtracted together.

15a-9a=6a
6a+20a=26a
26a-12a=14a
The simplest form is 14a <span />

Answer 2

0+1=1 
1-0=1
1x1=1
1/1=1
1 is in everything if this didnt help tell me