Case-1 a – b – 1 = 5 & a + b – 15 = 1 ⇒ a = 11, b = 5 Case-2 a – b – 1 = –5 & a + b – 15 = –1 ⇒ a = 5, b = 9 Case-3 a – b – 1 = 1 & a + b – 15 = 5 ⇒ a = 11, b = 9 Case-4 a – b – 1 = –1 & a + b – 15 = –5 ⇒ a = 5, b = 5