Problema Solution
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 16 cups of coffee, using 224 ounces of coffee, while collecting a total of $18.60. How many cups of each size did kyle fill?
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Lets assume that Kyle fill "a" 10-oz cups of coffee, "b" 14-oz cups of coffee and "c" 20 oz cups of coffee.
Then, according to the problem,
a + b + c = 16 (1)
10*a + 14*b + 20*c = 224 (2)
0.95*a + 1.15*b + 1.50*c = 18.60 (3)
Now, multiplying equation (1) by 10 and subtracting it from equation (2), we get
4b + 10c = 64 (4)
Again, multiplying equation (1) by 0.95 and substracting it from equation (3), we get,
0.2b + 0.55c = 3.4 (5)
Now,
Multiplying equation (5) by 20 and subtracting it from equation (4), we get
-c = -4,
Hence, c= 4
Putting this value in equation (4),
4b + 40 = 64
Hence, 4b = 24
So, b = 6
Again, putting the values of b and c in equation (1),
a + 6 + 4 = 16
Thus,
a = 6
Hence, the solution is
a = 6, 10oz cups of coffee
b = 6, 14 oz cups of coffee
c = 4, 20 oz cups of coffee