Fresh grapes contains 90% water, and dry grapes contains 85% matter. To get 25 kgs of dry grapes who many kgs of fresh grapes have to be processed?
Choose one:	A) 212	B) 212.5	C) 213.5	D) 213	E) None
Ans. To solve problems which involves 2 variables, concentrate on the variable that won't change. In this problem we concentrate on the variable matter rather than water as it changes.   Let us take K kgs of fresh grapes. Now total mater in these grapes = K x 10%   In 25 kgs dry grapes total mater = 25 x 85%   We know that these two equation are equal so   K X 10% = 25 x 85%   Solving K = 212.5   Answer 212.5
<result>B</result>
Fresh grapes contains 90% water, and dry grapes contains 85% matter. To get 25 kgs of dry grapes who many kgs of fresh grapes have to be processed?