SOLUTION: Angela needs 20 quarts of 50% antifreeze in her radiator. She plans to obtain this by mixing some pure antifreeze (100%) with an appropriate amount of a 40% antifreeze solution. Ho

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Question 24050: Angela needs 20 quarts of 50% antifreeze in her radiator. She plans to obtain this by mixing some pure antifreeze (100%) with an appropriate amount of a 40% antifreeze solution. How many quarts of each should she use?
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
You can set up the appropriate equation for this situation from the problem description.
Let x = the required number of quarts of pure (100%) antifreze, then (20-x) = the required number of quarts of 40% antifreeze solution which, when added together, will give 20 quarts of 50% antifreeze solution. Change the percentages to their decimal equivalents. The equation is:
x+%2B+%2820-x%29%280.4%29+=+20%280.5%29 Simplify and solve for x.
x+-+0.4x+%2B+8+=+10
0.6x+%2B+8+=+10 Subtract 8 from both sides of the equation.
0.6x+=+2 Divide both sides by 0.6
x+=+2%2F0.6 = 3 1/3
x = 3 1/3 quarts of pure antifreeze.
20-x = 16 2/3 quarts of 40% antifreeze.