A 30% salt solution is prepared by mixing a 20% salt solution and 45% salt solution. How many litres of each must be used to produce 60 L of the 30% salt ?

Question

Its is asking. How many litres of salt solution must be produced

Answer 1

(x L)(20%) + (60 L - x L)(45%) = (60 L)(30%)

20x + 2700 - 45x = 1800

25x = 900

x = 36 liters of 20%

plus 24 liters of 45%

 

 

Answer 2

Let x = number of liters of the 20% salt solution

Let y = the number of liters of the 45% salt solution

x + y = 60      y = 60 - x

.20x + .45y = .30(60)       Multiply both sides of the equation by 100.

20x + 45y = 30(60)

20x + 45y = 1800

20x + 45(60 - x) = 1800

20x + 2700 - 45x = 1800

-25x = -900

x = 36 liters

y = 60 - x = 60 - 36

y = 24 liters