word problem solving equations

Question

whats the x and y value

one canned drink is 30% orange juice; another is 5% orange juice. How many liters of each should be mixed together in order to get 25L that is 7% orange juice? How many liters of the 30?% orange juice should be in the? mixture?

Answer 1

X+Y =  25 ---> y  = 25-x

 

0.3X + 0.05Y = 25*0.07 = 1.75

 

30x + 5y = 175 <--- multiplies everything by 100 to clear away the decimals

 

30x + 5(25 - x) = 175

 

30x + 125 - 5x = 175

 

25x + 125 = 175

 

25x = 50

 

x=2

 

CHECK:

 2(0.3) + 23(0.05) = 1.75 = 0.07(25) <--- yes it works

 

2 liters of the 30% OJ and 23 liters of the 5% OJ