For number 16:
Use the vertical pencil line you have drawn to split the polygon.
12-4=8
3*8=24
12*4=24
24+24=48
48 is the area of 16
For number 17:
Split the polygon in half
Find the area of both of the parallelograms
6*20=120
6*20=120
120+120=240
The area of shape 17 is 240