Finding the sum of two numbers given the difference of LCM and GCD. 
l-h=57
Let, the two numbers be a and b.
Then,
     ab=lh

How to proceed further? Please give me just hints? They have asked the minimum value of the sum so, I think that I have to take different possibilities.

How about a=2 and b=29?
So lcm(a,b)-gcd(a,b)=57 and I'm just letting gcd(a,b)=1 so lcm(a,b)=58; since 58=2*29, therefore ...
