Linear Equation type of question (fuel mixture)

[usman77]

here is the question:

Premium gasoline sells for 78.9cents/Liters. Regular gas sells for 71.9 cents/ litres. To boost sales, a middle octane gasoline is formed by mixing premium and regular. If 1000 L of this middle octane gas is produced, and is sold at 73.9 cents/Litres, then how much of each type of gasoline can you assume was used in the mixture?

Answer : 600 L premium and 400 L regular.........i got the answer from the back of the buk.....but i m not able to solve this question and get this answer

help plz

 

[skeeter]

let x = amount of premium gas in liters
1000 - x = amount of regular gas in liters

x(.789) + (1000-x)(.719) = 1000(.739)

solve for x to determine the number of liters of premium

after you find x, 1000 - x will tell you the number of liters of regular

go for it.

 

[galactus]

That's exactly what I came up with, skeeter. The answer is not 600 and 400. I thought maybe I was doing something wrong.

 

[skeeter]

I did not check the answer ... just set up the equation.

 

[Denis]

Mr U.S. Man, them thingies all work this way:

  a   @ x
  b   @ y
=========
(a+b) @ z

z = (ax + by) / (a + b)