SOMEONE help me with this plz pretty plz

Liam's parents are driving three times as fast as liam is biking, but they left later than he did. if his parents caught up with him two hours after he left, how much later than liam did they leave?

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?