whatever% of anything, is just (whatever/100) * anything.
there were a total of 560000 votes, now, off those some are valid and some are invalid.
we know 15% of that are invalid, that simply means that 85% are valid, since 85% + 15% is the whole thing, or 100%, if 15% are not good, the other 85% are the good ones.
how many are the valid ones anyway? well, 85% of 560000, which is just (85/100) * 560000.
we know that off those valid ones, the candidate got 75% of those, so how much is 75% of that?
well, (75/100) * [ (85/100) * 560000 ].
