b. Tie the 3 specific people together. We can arrange them in 6 different ways. But we can also arrange them all in 24 different ways.

24*6=144 ways

c. tie the two people together and we can arrange them in 2 ways. We can arrange them all in 5! or 120 ways.

120*2=240.

But they DO NOT want to be together: 720-240=480 ways.