Question 1184101
<br>
Using the standard formal algebraic solution method....<br>
x = liters of 30% alcohol
12.5-x = liters of 80% alcohol<br>
The total amount of alcohol in the two ingredients is 60% of the total 12.5 liters:<br>
{{{.30(x)+.80(12.5-x)=.60(12.5)}}}<br>
I'll let you finish the solution by that method....<br>
Here is a quick and easy way to solve any 2-part "mixture" problem like this if a formal algebraic solution is not required....<br>
Consider the three percentages 30, 60, and 80 on a number line and observe/calculate that 60 is 3/5 of the way from 30 to 80.  (30 to 80 is a difference of 50, 30 to 60 is a difference of 30; 30/50 = 3/5.)
That means 3/5 of the mixture is the 80% alcohol.<br>
ANSWER: 3/5 of 12.5 liters, or 7.5 liters, of 80% alcohol; the other 5 liters of 30% alcohol.<br>
CHECK:
.80(7.5)+.30(5)=6+1.5=7.5
.60(12.5)=7.5<br>