Question 150397
The students from algebra class go for coffee together every day at 9:00 AM. 
On Monday, Jordan paid $5.45 for three cartons of milk, four cups of coffee, and seven doughnuts.
3M + 4C + 7D = 545
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On Tuesday, Ryan paid $5.30 for four milks, two coffees, and eight doughnuts.
4M + 2C + 8D = 530
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 On Wednesday, Zack paid $5.15 for two milks, five coffees, and six doughnuts.
2M + 5C + 6D = 515
 
(1) Set up a system of equations to model this scenario.
The system of three equations by any means you know to get:

M = $0.40
C = $0.45
D = $0.35
 
(2) Determine the cost of one carton milk, one coffee, and one doughnut by solving the system.
Solved above
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(3) If on Thursday, Taylor had to pay for five milks, two coffees and nine doughnuts, then how much did he spend?
5M+2C+9D = 5*40 + 2*45 + 9*35 = $6.05
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Cheers,
Stan H.