if x is less than y by 50 % then y exceed x by :
"using formula ( x / ( 100 - x ) * 100 ) where x is percentage decrease ( here it is 25 % ) = > 50 ( 100 - 50 ) * 100 = 100 % answer : b"
multiply(subtract(divide(const_100, subtract(const_100, 50)), const_1), const_100)