Answer:
Number of bags of chocolate chip cookies = x = 0.133 bags
Number of bags of walnuts = 7.7 bags
Explanation:
Chocolate chip cookies = 12oz per bag = $3
Walnuts = 4oz per bag = $2
She need 3 pounds of Chocolate chip cookies and Walnuts
Let us represent
Number of bags of chocolate chip cookies = x
Number of bags of walnuts = y
She need 3 pounds of Chocolate chip cookies and Walnuts
Hence,
We have to convert oz (ounces) to pounds
For chocolate chip cookies
1 oz = 0.0625 pound
12 oz = x
Cross Multiply
x = 12 × 0.0625 pound
x = 0.75pound
For Walnuts
1 oz = 0.0625 pound
4 oz = x
Cross Multiply
x = 4 × 0.0625 pound
x = 0.25pound
Hence,
0.75 pound = $3
0.25 pounds = $2
She can only spend $15
Chocolate chip cookies = 12oz per bag = $3
Walnuts = 4oz per bag = $2
Hence,
0.75x + 0.25y = 3..... Equation 1
3x + 2y = 15.... Equation 2
Multiply Equation 1 by 2 and Equation 2 by 0.25
1.5x + 0.5y = 3... Equation 3
1.5x + 4y = 30.... Equation 4
Subtract Equation 3 from 4
3.5y = 27
y = 27/3.5
y = 7.7 bags
Solving for x using Equation 2
3x + 2y = 15.... Equation 2
3x + 2(7.7) = 15
3x + 15.4 = 15
3x = 0.4
x = 0.4/3
x = 0.133 bags
Number of bags of chocolate chip cookies = x = 0.133 bags
Number of bags of walnuts = 7.7 bags