What is the answer to this math question?

The answer is option 3.

Step-by-step explanation:

First we have to find the area of both rectangle and triangle :

Rectangle,

Let base = 9,

Let height = 3,

Triangle,

Let base = 3,

Let height = 3,

Lastly, in order to find the shaded region you have to substract the area of triangle from the area of rectangle :

b.-4 units

all you   do is count how many times you move