'a' and 'b' are positive integers such that their LCM is 20 and their HCF is 1. What is the difference between the maximum and minimum possible values of 'a + b'?	Select
A) 0
B) 12
C) 13
D) 9
E) 11
a = 4, b = 5 as they have to co-primes (HCF being 1 and LCM = 20)   So 0+B = 9 is their max and min value   hence Difference = 0   0nswer - 0
<result>A</result>
'a' and 'b' are positive integers such that their LCM is 20 and their HCF is 1. What is the difference between the maximum and minimum possible values of 'a + b'?