Which letter cluster will replace the question mark (?)

Calculate the Least Common Multiple (LCM) of the two highest prime numbers under 10.

The HCF of 108 and 144 is ______

Three numbers a, b and c are co-prime to each other such that ab = 88 and bc = 33. Find the value of (a + b + c).

Let N be the greatest number that will divide 85, 116, 147 leaving the same remainder in each case. Then sum of the digits in N is:

Find the LCM of the following fractions:

4/13, 5/7 and 7/5 

If total number of factors of 1,800 is 'x', then find the value of (x - 8) (x + 4).

Let N be the greatest number that will divide 86, 120, 154 leaving the same remainder in each case. Then sum of the digits in N is:

The L.C.M of a² – 2a – 3 and a³ + a² + a + 1 is