<em>Okay so, im not the best at explaining, but so we have a percentage. its 25%. you want to take the 25% and put it over 100 because a percentage is a number or ratio expressed as a fraction of 100. so it will be written as 25%/100</em>
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<em>divide 25 by 100 and you get 0.25, correct? so that's one step further towards the answer.</em>
<em>then we write x/90 because we don't know (well we do) what we're gonna put. but, we're gonna multiply 0.25 by 90 and we get 22.5, which is equivalent to </em><em>22.50</em><em>.</em>