Ratio math problem?

How many litres of water should be added to a 30 litre mixture of milk and water containing milk and water to the ratio 7:3 so that the resultant ratio is 6:4

Bryce2016-03-26T01:20:24Z

Favorite Answer

7m/3w=21L of milk / 9L of water
21/(9+x)=6/4
84=54+6x
6x=30; x=5L of water

Anonymous2016-03-26T01:10:27Z

M:W
7:3
42:18(60u=30L)

Units of milk should be the same for before and after bc there's no change.

M:W
6:4
42:28

60u=30L
1u=2L
28u-18u=10u (units of amount water added)
10u=10x2L=20L (amount of water added)

Ans: 20L

Como2016-03-26T03:08:35Z

Milk_____Water_____Mixture
7_________3________10
21________9________30
21_______x + 9______x + 30

21 / (x + 9) = 6 / 4
84 = 6x + 54
30 = 6x
x = 5

5 litres of water to be added.

!!!2016-03-26T08:03:03Z

21:9 down to 18:12, 3 liter difference, add 3 liters of water, 33 liters/10=3.3,3.3x6=19.8, 3.3x4=:13.2