Select all pairs of positive integers that have HCF 6 and LCM 180
Note
If HCF×LCM = product of the two numbers, then the numbers must be 6×m and 6×n with m×n = 30 and gcd(m,n)=1; (12,90),(18,60),(30,36) satisfy this, while (24,45) does not have gcd 6.