The gcd(a, b) = 6, the lcm(a, b)=180. find the least possible value of a+b.

This is the concept of numbers, given that the G.C.D two numbers (a,b)=6 and the L.C.M (a,b)=180, to find the possible number we do as follows;
L.C.M =a*b=180
since 6 is a multiple of a and b, then the numbers could be:
180/6
=30
hence these numbers could be (6,30)