Final answer:
To make 12 cups that is 40% peanuts, 5 cups of the 12% peanuts mixture and 7 cups of the 60% peanuts mixture are needed.
Step-by-step explanation:
To find the number of cups of each mixture needed to make 12 cups that is 40% peanuts, we can set up a system of equations.
- Let x be the number of cups of the 12% peanuts mixture.
- Then, (12/100)x is the amount of peanuts in the 12% peanuts mixture.
- Since the mixture is 12%, we have (12/100)x = 0.12x cups of peanuts.
- Similarly, (60/100)(12 - x) is the amount of peanuts in the 60% peanuts mixture.
- Since the mixture is 60%, we have (60/100)(12 - x) = 0.60(12 - x) cups of peanuts.
- Now, we can set up the equation: 0.12x + 0.60(12 - x) = 0.40(12).
- Simplifying this equation, we get 0.12x + 7.2 - 0.60x = 4.8.
- Combining like terms, we have -0.48x = -2.4.
- Dividing both sides by -0.48, we find that x = 5.
Therefore, 5 cups of the 12% peanuts mixture and 12 - 5 = 7 cups of the 60% peanuts mixture are needed to make 12 cups that is 40% peanuts.