SOLUTION: There is a bottle of oil. First pour out 1/4 of the oil. Second, pour out 2/5 of the rest. The 2nd pour used 0.25kg more than the first pour. How much kg was poured the first time?

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: There is a bottle of oil. First pour out 1/4 of the oil. Second, pour out 2/5 of the rest. The 2nd pour used 0.25kg more than the first pour. How much kg was poured the first time?      Log On

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Question 1163594: There is a bottle of oil. First pour out 1/4 of the oil. Second, pour out 2/5 of the rest. The 2nd pour used 0.25kg more than the first pour. How much kg was poured the first time?
Answer by ikleyn(52814) About Me  (Show Source):
You can put this solution on YOUR website!
.

Let x be the first amount of oil, poured out (in kilograms).


Then the rest was 3x kilograms.


Second pour out was  %282%2F5%29%2A3x = %286%2F5%29x kilograms.


We are given that the difference was 0.25 kilograms :


    %286%2F5%29x - x = 0.25.


From this point, there is one step to get the answer


    %281%2F5%29x = 0.25

    x = 5*0.25 = 1.25 kilograms.


ANSWER.  1,25 kg was poured out the first time.

Solved.

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The major lesson to learn from my solution is how I choose my major unknown.

I choose it in this way to avoid working with the forest of fractions.