The total number of squares is 6x6 = 36
the number of squares of the shaded area is 3x4 = 12
We find the ratio by dividing those two quantities:
[tex]\frac{12}{36}=\frac{1}{3}[/tex]We find the percentage by multiplying the result by 100%
[tex]\frac{1}{3}\times100=0.333\times100=33.33[/tex]