Five-sevenths 4789

Forty-two liters of water fill the barrel to two-thirds of its volume. How many liters of water do we need to add if it is filled to five-sevenths of a volume?

Correct answer:

x =  3 l

Step-by-step explanation:


42 = 2/3·V
42 + x = 5/7·V

2V = 126
5V-7x = 294

Pivot: Row 1 ↔ Row 2
5V-7x = 294
2V = 126

Row 2 - 2/5 · Row 1 → Row 2
5V-7x = 294
2.8x = 8.4


x = 8.4/2.8 = 3
V = 294+7x/5 = 294+7 · 3/5 = 63

V = 63
x = 3

Our linear equations calculator calculates it.



Did you find an error or inaccuracy? Feel free to write us. Thank you!







Tips for related online calculators
Need help calculating sum, simplifying, or multiplying fractions? Try our fraction calculator.
Do you have a linear equation or system of equations and looking for its solution? Or do you have a quadratic equation?
Tip: Our volume units converter will help you convert volume units.

You need to know the following knowledge to solve this word math problem:

Related math problems and questions: