Question 353272
Hi,
Let x represent the "total" amount of the 14% solution to be added.
Then (20L + x) would be the total amount of the final 30% solution.
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question states
.14x + .50*20L = .30( 20L + x)
10L - 6L = .30x - .14x
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4L = .16x
x = 25L of the 14% solution needs to be added
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Check our answer
.14*25 + .50*20 = .30*45
  3.5   + 10    = 13.5