Ravi walks by the same speed and takes a round of a circular park in $18$ min and Meena takes a round of the same park in $12$ min. If they start at the same time from the same point, then after how many minutes, they will meet again at the same point.

Find the ratio of the LCM and the HCF of 5, 25 and 30. 

(A) 1 : 6 

(B) 30 : 1 

(C) 1 : 30 

(D) 6 : 1 

Find the HCF of 3, 7 and 15. 

(A) 7 

(B) 15 

(C) 3 

(D) 1 

Find the G.C.F and L.C.M of $20$and $28$.

1. $20, 280$
2. $5, 280$
3. $10, 140$
4. $4, 140$

What will be the HCF of $\frac{2}{3}, \frac{8}{9}$ and $\frac{64}{81}$?

The LCM of two numbers is $210$. If their HCF is $35$ and one of the numbers is $105$, find the other number: