Given the two sets, which statement is true?

a = {1, 2}

b = {1, 2, 3, 4}

a. b c a

b. 3 c a

c. 4 c a

d. a c b

e. none of the above

Two friends are reading books. jimmy reads a book with 21,356 words. his friend bob reads a book with one-and-a-half times as many words. which expression represents the number of words bob reads?