Now, notice the picture below
is really just one rectangle and a circle, well, half a circle or a semi-circle
so.... if you get the area of the whole rectangle, 16*19
and subtract, the area of half the circle, you end up with the shaded area
since, what you'd be leftover is, the rectangle, with a semi-circular hole, that was subtracted

now... let's say, you get an amount of hmmm [?]
ok, how much is that in percentage? well, 16*19 is 304
so, if we take 304 as the 100%, how much is [?] in percentage?

solve for "x"