So,
There are 4 red marbles.
There are 7 blue marbles.
There are 5 green marbles.
There are 16 marbles in total.
a.
Answer = (probability of selecting a red marble)(probability of selecting a blue marble)
First, the probability of selecting a red marble.

Next, the probability of selecting a blue marble.

Multiply the probabilities together.

That is the probability for event a.
b.
Answer = (probability of selecting a red marble)(probability of selecting a blue marble)
First, the probability of selecting a red marble.

Next, the probability of selecting a blue marble WITH A RED MARBLE REMOVED.

Multiply the probabilities together.

That is the probability for event b.
c.
Obviously:

So the answer is no.