Solution 3092

How many liters of 80% alcohol need to be mixed with 4 liters of 40% alcohol to get 70% alcohol? How many liters of 70% solution do we get?

Correct answer:

x =  12
y =  16

Step-by-step explanation:


0.80 x + 0.40·4 = 0.70 · y
y = x+4

0.80·x + 0.40·4 = 0.70 · y
y = x+4

0.8x-0.7y = -1.6
x-y = -4

Pivot: Row 1 ↔ Row 2
x-y = -4
0.8x-0.7y = -1.6

Row 2 - 0.8 · Row 1 → Row 2
x-y = -4
0.1y = 1.6


y = 1.6/0.1 = 16
x = -4+y = -4+16 = 12

x = 12
y = 16

Our linear equations calculator calculates it.



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