The number of hours needed to assemble computers varies directly with the number of computers. If 12 computers can be assembled in 9 hours , how many computers can be assembled in 15 hours ? Write a direct variation equation to solve.

Rose and andrew are financing $128,000 to purchase a condominium. they obtained a 15-year, fixed-rate loan with a rate of 5.05%. they have been given the option of purchasing up to four points to lower their rate to 4.81%. how much will the four points cost them?