Question 930829
Here's a similar problem:
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How much decaffeinated coffee(assume to be 0% caffeine)and 40% caffeine coffee should be mixed to produce 20 mugs of 30% caffeine coffee?
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d = decaf
c = regular
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d + c = 20  (total mugs)
0*d + 40*c = (0 + 40)*30  (total caffeine)
40c = 1200
c = 30 mugs
d = 10 mugs