Which is the graph of the given function f(t)=2cos(-4t)

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?

What is number 31 as a sum of tens and ones?

Which statement is true about the graphs of the two line y=-8x-5/4 and y=1/8x+4/5