Question 281530
This one is often a tricky one, I see this problem every once in a while:

please note that 25 percent is .25, however, if we multiply both sides by a hundred, this becomes 25. You will see what I mean below:

We will need to set up the equation as, percent times how much we put in:

{{{25(x) + 50(6) = 30(x + 6)}}}

Now for explaining how I got this:
We need 25 percent of X gallons, I put x because it doesn't say how many. We also need 50 percent of 6 gallons, which will make a total of 30 percent of (x + 6), we get x + 6 by adding up x and 6. If I were to multiply both sides by a hundred the percent signs get taken off and unfortunately there is technical problems when using decimal so I had to remove them early, now to solve:

{{{25x + 300 = 30x + 180}}}
{{{120 = 5x}}} => {{{5x = 120}}}
{{{x = 24}}}

We will need 24 gallons of 25% alcohol with 6 gallons of 50% alcohol to make 30% alcohol solution.