Find the sum.
( - x - 2y - 4z ) + ( 7x - 6y - 6z )

Stephen thublin invests $1,000,000 in a 45-day certificate of deposit with 6.55% interest. what is the total interest income from the investment?

Find the commission on a $590.00 sale if the commission is 15%.

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).