Question

A store is having a sale on walnuts and chocolate chips. For 7 pounds of walnuts and 9 pounds of chocolate chips, the total cost is $37. For 5 pounds of walnuts. and 3 pounds of chocolate chips, the total cost is $17. Find the cost for each pound of walnuts and each pound of chocolate chips.​

Answer 1

• Walnuts cost $1.75, chocolate chips cost $2.75

Explanation:

Let the costs be:

• Walnuts - x
• Chocolate chips - y

Set equations as per question

For 7 pounds of walnuts and 9 pounds of chocolate chips, the total cost is $37:

• 7x + 9y = 37

For 5 pounds of walnuts and 3 pounds of chocolate chips, the total cost is $17:

• 5x + 3y = 17

Solve the system by elimination

Multiply the second equation by 3 and subtract the first equation, solve for x:

• 3(5x + 3y) - (7x + 9y) = 3(17) - 37
• 15x + 9y - 7x - 9y = 51 - 37
• 8x = 14
• x = 14/8
• x = 1.75

Find the value of y:

• 7*1.75 + 9y = 37
• 12.25 + 9y = 37
• 9y = 37 - 12.25
• 9y = 24.75
• y = 24.75/9
• y = 2.75