I think that it is geometry.
Answer:
5 gallons of water must be added.
10 gallons to start with
adding 'x' gallons of water final volume = 10 + x
.9 (10) = amount of vinegar
.1(10) = amount of water
amount of vinegar before and after water addition is constant
.9(10) = .6(10+x)
9 = 6 + .6x
3 = .6x
x = 5 gallons of water to be added
(i truly hope i helped you
It would be X=3 because 3 multiplied by 1 equals 3 and you get 3 over 21. that simplifies to 1 over 7.
