DSE 2016 doubt

Posted by ecom on Jun 29, 2017; 7:38pm
URL: http://discussion-forum.276.s1.nabble.com/DSE-2016-doubt-tp7606646.html

Can anybody please help with questions 18 and 21 from the 2016 paper please :)
18 is stupid doubt, i know. But i'm stuck on it :(