If sum of two numbers is 1215 and their HCF is 81, then the possible number of pairs of such numbers are

(a) 2   (b) 3   (c) 4   (d) 5

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Question 21 If sum of two numbers is 1215 and their HCF is 81, then the possible number of pairs of such numbers are (a) 2 (b) 3 (c) 4 (d) 5 Since HCF of both numbers is 81 It means 81 is a factor of both numbers Thus, let us assume numbers are 81x and 81y Where x and y are co-prime numbers Now, given that Sum of numbers = 1215 81x + 81y = 1215 81(x + y) = 1215 (x + y) = 1215/81 x + y = 15 Here, x and y are co-prime numbers So, Possible values of x and y can be 1 and 14 2 and 13 4 and 11 7 and 8 Thus, there are 4 such pairs So, the correct answer is (c)

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo