Question 190731
Adjusting Antifreeze: Angela needs 20 quarts of 50% antifreeze solution
 in her radiator. She plans to obtain this by mixing some pure antifreeze
 with an appropriate amount of a 40% antifreeze solution.
 How many quarts of each should she use?
:
Let x = amt of 40% solution to be removed
and
Let x = amt of pure antifreeze to be added
:
.4(20-x) + 1.0x = .50(20)
:
8 - .4x + 1x = 10
:
-.4x + 1x = 10 - 8
:
.6x = 2
x = {{{2/.6}}}
x = 3{{{1/3}}} qts removed and added
;
:
Check:
.4(16.67) + 1(3.33) = .5(20)
6.67 + 3.33 = 10