Question 700547
Julia mixes 10 liters of 6% acidic solution with a specific amount of a 12% acidic solution, which results in an 8% acidic solution.
  Find the number of liters of 12% acid solution in the new mixture.
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Let x = the specific amt of 12% solution
:
A typical mixture equation
.06(10) + .12x = .08(x+10)
.6 + .12x = .08x + .8
.12x - .08x = .8 - .6
.04x = .2
x = .2/.04
x = 5 liters of 12% solution required 
:
:
Check this
.06(10) + .12(5) = .08(5+10)
.6 + .6 = .08(15)
1.2 = 1.2; confirms our solution of 5 liters