Question 421293
A solution of 54% fertilizer is to be mixed with a solution of 27% fertilizer to form 135 liters of a 49% solution. How many liters of the 54% solution must be used? 
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f = 54%
t = 27%
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f + t = 135 (total solution)
0.54f + 0.27t = 0.49*135 (total fertilizer)
Can you finish it?