Thank you all for your responses.....I only got 2/4 correct, whereas my daughter received 100%.

The answers are:

(Find the least common multiple of the monomials)
3S, S2(S squared).............. LCM= 3S cubed
X4 (X to the 4th power), X2( X squared).................LCM=X to the 4th
15m2 (15m squared), 9m..........................LCM=45m2 (45M squared)
8b, 20b2(20b squared) .......................LCM=40b2 (40b squared)

Have a great weekend.