One fourth of a solution that was 10% sugar by weight was replaced by a second solution resulting in a solution that was 18percent sugar by weight. The second solution was what percent sugar by weight?
Choose the correct choice from the following options
A) 34 %	B) 24 %	C) 42 %	D) 18 %	E) 8.5 %

Rationale: "instead of using complex calculations and remembering formulae , why dont u directly get to weighted average . 3 parts of 10 % + 1 part of x ( unknown ) % = 4 parts of 18 % = > x % = 72 % - 30 % = 42 % ans c it is ."
Answer: C