D. Write an equation to represent each of the following. Write your answer on the space provided. 16. The sum of a number and five is twelve. 17. Twice a number decreased by six is equal to sixteen. 18. If nine is added to the difference of a number and nineteen, the sum is ninety. 19. Twice the sum of a number and two is twenty-two 20. The sum of a number and ten is twenty