Sources of finance - equity

Sir when examiner ask "what % of rights could I take up in order for there to be no change in my cash balance" , referring back to your example 2 Can we do it this way ' taking the "value of a right" we divide it by "vlaue of share after rights issue" (ex-right m.v) like in your example 1.50 (value of a right) / 7.50 (ex-right m.v) effectively got 20% instead of doing the balancing figure like you did will I get the same answer to all questions asking same thing? :p clear me Sir because I think this way is the quickest one for MCQ (if examine) :)