An irregular polygon is shown below:

the area of the irregular polygon is square units.
numerical answers expected!

You can split this shape into two shapes; a rectangle on top and a horizontal rectangle underneath. The top rectangle would be 4 x 2 = 8 square units, and the bottom rectangle would be 7 x 1 (3 - 2) = 7 square units. Now you just add these to get 15 square units. I hope this helps!