I am unable to understand the “converse” side of the problem . Is is A-B = 45 and B-A = 54 ? Could someone help me coming to the solution here ?

Since A is in the tens place and B is in units place in the initial AB its 10A+B

it’s (10A+B)-(10B+A)=54

A-B=6

since A and B had to be positive integers choose numbers for A>6 and B>0

for example A=7 and B=1 so it satisfies A-B=6 similarly you need to find the other pairs