Hi! I'm happy to help!
Perimeter is the total length of all the sides.
Let's start out with the top left corner and work our way counterclockwise.
For our first segment, we start from the top left corner and go to the bottom left corner, this is a length of 3, let's start our equation:
3+
Next, we are at the bottom left corner, let's go to the bottom right corner. This is a length of 5. Let's expand our equation:
3+5+
Now we are at the bottom right corner, let's go to the top right corner. This is also a length of 3. Let's add that to our equation:
3+5+3+
Now we are at the top right corner, lets go to the top middle right corner, which is to the left one unit. Let's add this:
3+5+3+1+
Now, let's head down 2 units to the inside of our shape.
3+5+3+1+2+
Move toward the center one unit:
3+5+3+1+2+1+
Move up one unit:
3+5+3+1+2+1+1+
Move left one unit:
3+5+3+1+2+1+1+1+
Move down one unit:
3+5+3+1+2+1+1+1+1+
Move left another unit:
3+5+3+1+2+1+1+1+1+1+
Start heading back up 2 units towards the top left corner:
3+5+3+1+2+1+1+1+1+1+2+
Finally, reach back 1 unit to the top left corner:
3+5+3+1+2+1+1+1+1+1+2+1=
Let's solve:
3+5+3+1+2+1+1+1+1+1+2+1=
8+3+1+2+1+1+1+1+1+2+1=
11+1+2+1+1+1+1+1+2+1=
12+2+1+1+1+1+1+2+1=
14+1+1+1+1+1+2+1=
15+1+1+1+1+2+1=
16+1+1+1+2+1=
17+1+1+2+1=
18+1+2+1=
19+2+1=
21+1=
22
Our perimeter is 22.
I hope this was helpful,(I think this was longer than it needed to be) keep learning! :D