Question

which is number less than 100 , which increases 1/5th of its value when you interchange the digits ?"

Answer 1

When it is reversed it is 10b + a = 12a+1.2b
11 a = 8.8b 
a/b = 8.8/11 = 0.8/1 = 8/10 = 4/5
answer is 45