What's the difference 7/4-1/8

Find an equation (in term of x) of line through the points (-1,3) and (1,4)

Based on what i know about mean, this doesn't add up.

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?