ques4-https://www.actuariesindia.org/downloads/exampapers/OctNov06/qpapers/ASI_QP_CT3_1006.pdf solution- question 4-https://www.actuariesindia.org/downloads/exampapers/OctNov06/Sol%20Oct-Nov/ASI_IS_1006_CT3.PDF pls explain why do we take x-y and x+y or any other numerical sign. Moreover why do we take e^-(x-y) why - sign. Thanks & Regards, Anjum