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From the condition, you have this system of 2 equations in 2 unknowns
4x + 8y = 21 (1)
2x + 3y = 9 (2)
where x is the price of one pound of walnuts and y is the price of one pound of chocolate chips.
Solve this problem by any way you want / you know / you prefer.
For example, you may start multiplying the second equation by 2 (both sides) and then subtracting it
from the first equation.
Wish you successfully complete the solution on your own (!)
If you have questions, do not hesitate post them to me.