Answer:
We should use 30 pints of the first drink and 120 pints of the second drink
Explanation:
Let x represent the number of pints of the first drink used
Volume of fruit juice in x pints = 35% of x = 0.35x
Let y represent the number of pints of the second drink used
Volume of fruit juice in y pints = 85% of y= 0.85y
Since the final mixture volume is 150 pints we get
x + y = 150 ..... [1]
If the final mixture has to contain 75% pure fruit juice, the volume of fruit juice in the mixture = 0.75 x 150 = 112.5 pints
Therefore
0.35x + 0.85y = 112.5 ...[2]
We will solve this set of simultaneous equations by making the coefficients of one of the variables equal and then subtracting to eliminate that variable
Multiply equation [1] by 0.35 to get the x coefficients equal
0.35 x [1]
=> 0.35(x + y) = 0.35(150)
=> 0.35x + 035y = 52.5 ... [3]
Subtract [3] from [2]:
[3] - [2] =>
0.35x + 0.85y - (0.35x + 035y) = 112.5 - 52.5
0.35x + 0.85y - 0.35x - 0.35y = 60
0x + 0.5y = 60
0.5y = 60
y = 60/0.5
y = 120
Therefore x = 150 - 120 = 30
Therefore we should use 30 pints of the first drink and 120 pints of the second drink