10 kg of nuts
20 kg of cereal
I am going to assume that there's a typo in the question. There is no possible combination of two items where one costs $2.50/kg and the other costs $11.00/kg where the result is worth $1.50/kg. But if the cereal actually costs $1/kg, then there is a solution. That is the solution I'll show.
N = amount of nuts
(30-N) = amount of cereal
The overall equation is
2.50N + 1.00(30-N) = 30*1.50
Now solve for N. First distribute the 1
2.50N + 30 - N = 30*1.50
2.5N + 30 - N = 45
1.5N + 30 = 45
1.5N = 15
N = 10
So you need 10 kg of nuts and 30-10 = 20 kg of cereal.
Let's verify the results
10*2.50 + 20 * 1.00 = 25.00 + 20.00 = $45.00
$45.00 / 30 kg = $1.50/kg
