a -bc-d--4 -2a + b +3c 2d 5 MODELING Write a system of linear equations for each

Question

a -bc-d--4 -2a + b +3c 2d 5 MODELING Write a system of linear equations for each problem and solve the system using Gaussian elimination. 67. Wages from Two Jobs Mike works a total of 60 hr per week at his two jobs. He makes $8 per hour at Burgers-R-Us and $9 per hour at the Soap Opera Laundromat. If his total pay for one week is $502 before taxes, then how many hours does he work at each job? 68. Postal Rates Noriko spent $23.20 on postage inviting a total of 60 guests to her promotion party. Each woman was sent a picture postcard showing the company headquarters in Tokyo while each man was invited with a letter. If she put a 28-cent stamp on each postcard and a 44-cent stamp on each letter, then how many guests of each gender were invited? 69. Investment Portfolio Petula invested a total of $40,000 in a no-load mutual fund, treasury bills, and municipal bonds. Her total return of $3660 came from an 8% return on her investment in the no-load mutual fund, a 9% return on the treasury bills, and a 12% return on the municipal bonds. If her total investment in treasury bills and municipal bonds was equal to her investment in the no-load mutual fund, then how much did she invest in each?

Explanation / Answer

67.

Let Mike works for x hours per week at Burgers-R-Us and y hours per week Soap Opera Laundromat.

So, acc to question,

x + y = 60......(1)

8x +9y = 502.......(2)

Multiplying (1) by 8, we get

8x + 8y = 480.....(3)

Subtracting (3) from (2), we get

y = 22

Putting this value in (1) , we get x = 38

So, Mike works for 38 hours per week at Burgers-R-Us and 22 hours per week Soap Opera Laundromat.

Please upvote.Thank you.

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