<PRE><B>Question 412385</B>
x = amount of coffee worth 18 per kilo.
y = amount of coffee worth 9 per kilo


x + y = 90
18*x + 9*y = 12*90


from the first equation, you get y = 90 - x


substitute in the second equation to get:


18*x + 9*(90-x) = 12*90


simplify to get:


18*x + 810 - 9x = 1080


combine like terms and subtract 810 from both sides of the equation to get:


9x = 270


divide both sides of the equation by 9 to get:


x = 30


if x = 30, then y = 90-30 = 60.


your answer should be x = 30 kilo and y = 60 kilo.


30 * 18 = 540
60 * 9 = 540


540 + 540 = 1080 php total.


30 kilo at 18 php per kilo plus 60 kilo at 9 php per kilo will result in 90 kilos for a total of 1080 php.


1080 / 90 = 12 php per kilo.


your answer is confirmed as correct.







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