a' and 'b' are positive integers such that their LCM is 20 and their HCF is 1. What is the addition between the maximum and minimum possible values of 'a - b'?  Choose the correct choice from the following answers.
A) 0  B) 12  C) 24  D) 26  E) 18
possible values of a and b can be 5,4; 4,5 and 1,20; 20,1   maximum possible value for a-b is   20-1= 
<gadget id="calculator">  20-1</gadget>
<output>19</output>
19   minimum possible value for a-b is 1-20=-19   19-19= 
<gadget id="calculator">19-19</gadget>
<output>0</output>
0 ans is 0
<result>A</result>
a' and 'b' are positive integers such that their LCM is 20 and their HCF is 1. What is the addition between the maximum and minimum possible values of 'a - b'?