please help

1. 4*3/2-1*2/2+1*1=6

2.4*4-(3*4/2)-(4*3/2)=4

3.4*4-1-1/2-(3*3/2)-(1*4/2)-((1*2/2)*2)=6

You can use Pick's formula:

     Area  =  (Number of Boundary Points) / 2 + (Number of Interior Points) - 1

 

The top figure:  Number of Boundary Points = 10

                         Number of Interior Points = 2

--->   Area  =  (10/2) + 2 - 1  =  5 + 2 -1  =  6

 

This formula can also be used for the other two figures resulting in the same answers as given by the other person.