Can someone help me with this question please.

Answer:
a. +3
b. -12a
Step-by-step explanation:
Here, we want to know the steps that are involved in those unoccupied segments
let’s start with the output
6a + 18
So what turned a to 6a + 18
Let’s call that output x
Let’s reverse the last step that multiplied that term and a
Thus (6a + 18)/6 = a + 3
Thus the x-term we are looking for is + 3 before the multiplication by 6
Now for the second part;
a * 4 -3 = -12a