45.4k views
0 votes
help. Sarah would like to make a 5 lb nut mixture that is 60% walnuts and 40% cashews . She has several pounds of walnuts and several pounds of a mixture that is 20% walnuts and 80% cashews . Let w represent the number of pou nds of walnuts needed to make the new mixture, and let m represent the number of pounds of the 80% cashew - 20% walnut mixture. (a) Write a system of linear equations that models this situation . (b) Which of the following is a solution to the system: 2 lb walnuts and 3 lb mixture OR 2.5 lb walnuts and 2.5 lb mixture? Show your work.

1 Answer

4 votes

Answers:


a) w+c = 5 ____equation(1) and w = c ____equation (2)


b) 2.5 lb walnuts and 2.5 lb cashews


Explanation:


Let w pounds be the weight of walnuts required and c pounds be the weight of cashews required to make the new mixture.


Total weight of the new mixture = 5 lb


So,


Weight of walnuts + Weight of cashews = Total weight of the new mixture


w+c = 5 ____equation (1)


Now,


60% of walnuts +40% of cashews = 20% of walnuts + 80% of cashews


0.60w+0.40c = 0.20w+0.80c


Subtracting 0.20w from both the sides of the equation, we get


0.60w+0.40c-0.20w = 0.20w+0.80c-0.20w


Cancelling out the 0.20w and -0.20w from the right side, we have


0.60w-0.20w+0.40c = 0.80c


=> 0.40w+0.40c=0.80c


Subtracting 0.40c from both sides, we get


0.40w+0.40c-0.40c=0.80c-0.40c


Cancelling out 0.40c and -0.40 c form the left side, we get


0.40w = 0.40c


Dividing both sides by 0.40, we have


\frac{0.40w}{0.40} = \frac{0.40c}{0.40}


Cancelling out the 0.40's from the top and bottom, we get


w = c ____equation (2)


Plugging in w=c into the equation 1, we get


w+c = 5


=> c+c =5


=> 2c = 5


Dividing both sides by 2, we get


\frac{2c}{2} = \frac{5}{2}


Cancelling out the 2's from the left, we get


c = 2.5


Plugging in c=2.5 into the equation 1, we get


w+c = 5


=> w + 2.5 = 5


Subtracting 2.5 from both sides, we get


w+ 2.5 -2.5 = 5 - 2.5


Cancelling out the +2.5 and -2.5 from the left side, we get


w = 2.5


So, we need 2.5 lb walnuts and 2.5 lb cashews to make the new mixture.


- R3KTFORGOOD ☕


User Srnka
by
5.6k points