00:02
Alrighty, i'm going to say x equals the amount of amount, oops, let's fix that, amount of 5 % acid, and y is going to be our amount of 20 % acid, and c is going to be our amount of water.
00:33
All right and we know all together we want 10 ounces so we can say x plus y plus c equals 10 and just so we're clear with variables we can make them whatever we want i made it c just because that's easier than z because sometimes z look like twos anyways we know that water is going to equal the other two combined.
01:05
So we can say c equals x plus y.
01:09
And we know altogether we need to make a solution that is 8 .5 % acid.
01:16
So we can say the amount of 5 % times 5 % plus the amount of 20 % times 20 % plus the amount of water times 0.
01:30
Since your water is 0 % acidic has to equal 10 times .085.
01:42
So that goes away.
01:46
We know that c equals x plus y and x plus y plus c equals 10.
01:58
So what if i said x plus y plus x plus y equals 10? we would have 2x plus 2y equals 10.
02:12
And then i could get x by itself and say 2x equals 10 minus 2y and then divide by 2.
02:21
So we would get x equals 10, nope, 5 minus y.
02:29
So now we can plug this in down here...