SOLUTION: I would be grateful to have some help with this problem: Kyle works at a donut​ factory, where a​ 10-oz cup of coffee costs 95¢​, a​ 14-oz cup costs&#8203

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Question 1125749: I would be grateful to have some help with this problem:
Kyle works at a donut​ factory, where a​ 10-oz cup of coffee costs 95¢​, a​ 14-oz cup costs​ $1.15, and a​ 20-oz cup costs​ $1.50. During one busy​ period, Kyle served 28 cups of​ coffee, using 404 ounces of​ coffee, while collecting a total of ​$33.30. How many cups of each size did Kyle​ fill?
Kyle filled
___10-oz cup(s),
___14-oz cup(s), and
​___20-oz cup(s).
Answer by josgarithmetic(39623) About Me  (Show Source):
You can put this solution on YOUR website!
SIZE(oz)          PRICE        CUPS       REVNU
10                0.95         x           0.95x
14                1.15         y           1.15y
20                1.50         z           1.50z
TOTAL, 404                    28          33.00

system%2810x%2B14y%2B20z=404%2Cx%2By%2Bz=28%2C0.95x%2B1.15y%2B1.5z=33%29

system%285x%2B7y%2B10z=202%2Cx%2By%2Bz=28%2C19x%2B22y%2B30z=660%29


results
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system%28x=12%2Cy=6%2Cz=10%29
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(used http://matrix.reshish.com/gaussSolution.php )