Well let's see.
If the figure is split up into 10 pieces, then
each piece is 1/10 of the whole figure.
If 2 of the pieces are shaded, then
2/10 of the whole figure is shaded.
How many pieces are left ?
There were 10 pieces all together, and
2 of them are shaded. Hmmm. I think
there are probably (10 - 2) = 8 of them left
that are not shaded.
8 pieces makes 8/10 of the whole figure.