13. In the following ordinary annuity, the interest is compounded with each payment, and the payment is made at the end of the compounding period.

You and your new spouse each bring home$1600 each month after taxes and other payroll deductions. By living frugally, you intend to live on just one paycheck and save the other in a mutual fund yielding7.85% compounded monthly. How long will it take to have enough for a 20% down payment on a$165,000 condo in the city? (Round your answer to two decimal places.)

Yr

25. Express the situation as a system of two equations in two variables. Be sure to state clearly the meaning of yourx- andy-variables. Solve the system by row-reducing the corresponding augmented matrix. State your final answer in terms of the original question.

For the final days before the election, the campaign manager has a total of$50,500 to spend on TV and radio campaign advertisements. Each TV ad costs $3000 and is seen by 10,000 voters, while each radio ad costs $500 and is heard by 2000 voters. Ignoring repeated exposures to the same voter, how many TV and radio ads will contact178,000 voters using the allocated funds?

x	=	TV ads
y	=	radio ads

26. Find the augmented matrix representing the system of equations.

x₁ +x₂ +x₃ =4

x₁ +2x₂ +x₃ =3

x₁ +2x₂ +3x₃ =2

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