From the given figure we can see that
The pattern increases 2 squares every time, 1 horizontal and 1 vertical
a)
Figure 4 has 5 horizontal squares and 4 vertical squares
Figure 5 has 6 horizontal squares and 5 vertical squares
b) The pattern increases by 2 squares every time
That because
Figure 1 has 3 squares
Figure 2 has 5 squares
Figure 3 has 7 square
5 - 3 = 2, 7 - 5 = 2
Then the pattern increases by 2
c.
To find the number of squares for the 100th term, we will use the equation
Substitute n by 100
There are 201 tiles in figure 100