Question

How many gallons of a 80% alcohol solution and a 30% alcohol solution must be mixed to get 10 gallons of a 70% alcohol solution?
80% solution is= to how many gallons
30% solution is = to how many gallons

Answer 1

look at just the alcohol content. If there are x gallons of 80%, then the rest (10-x) must be 30%. So,
80x + 30(10-x) = 70*10

Answer 2

I don't understand your answer

Answer 3

0.80x is the amount of alcohol in x gallons of 80% mix.
0.30(10-x) is the amount in the 30% mix
if you add them up, the amount of alcohol must be the same as that in 10 gallons of 70%.

I just multiplied everything by 100 to get rid of the pesky decimals.

So, if you solve that, you get x=8
to check, note that 80% of 8 gals is 6.4 gals of alcohol
30% of 2 gals is 0.6 gals
70% of 10 gals is 7 gals, which is 6.4 + 0.6
so the equation works.

Answer 4

Thank you