Answer:
f(n) = 2 + 2(n+1)
Explanation:
We cannot tell from your photo exactly what Kyle's coloring is. It appears that he might have colored the top bar and the bottom bar of each figure. These bars have one more square than the figure number. There are two other squares between the bars that are not colored.
Then the number of squares in figure n will be the total of the two uncolored squares and twice the number in the bottom row. That is, the number of squares could be described as ...
f(n) = 2 + 2(n+1)