Try to split up the face into pieces. You can make the first piece the square on the top. Only, you don't know the value of the bottom side, but you can see that it is 10 (if you look at the top at the back). So, if you do your multiplication, 10 x 10 = 100. So, that is the area of the first square. The next square also has a width and height of 10, (10 on the bottom, and follow the side to the other 10). Do the multiplication again (same as above) and get 100. Now that you have the area of the two pieces, you add then together: 100+100=200
Please feel free to let me know if you have any questions!
