a) A bookcase shelf has 2 Calculus textbooks, 5 Statistics textbooks, 3 Physics textbooks, and 5 LinearAlgebra textbooks. textbooks. what is number of waysna student can choose one ofeach type of textbooks. ( choose the correct answer: n= 50 or 12 or 25 or 150 or 15)

b) There are 3 subway lines from city T to city Y and 8 subway lines from city Y to city R. What is the number of ways that a person can have a round-trip fromTtoRviaYwithoutusing each subway line more than once ( choose the answer 20 or 336 or 22 or 384 or 576)

c)There are 3 subway lines from city T to city Q and 8 subway lines from city Q to city R. What is the number of ways that a person can have a round-trip fromTtoRviaQ ( choose the right answer 11 or 27 or 48 or 24 or 576)

d)There are 3 subway lines from city T to city Q and 8 subway lines from city Q to city R. What is the number of lines that a person can travel fromTtoRviaQ (choose the right answer: 11 or 24 or 35 or 48 or 576)