A merchant wishes to mix two grades of peanuts costing $3 and $4 per pound, respectively, with cashews costing $8 per pound to obtain 140 pounds of a mixture costing $6 per pound. If the merchant also...

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Extracted text: A merchant wishes to mix two grades of peanuts costing $3 and $4 per pound, respectively, with cashews costing $8 per pound to obtain 140 pounds of a mixture costing $6 per pound. If the merchant also wants the amount of lower grade peanuts to be twice that of the higher grade peanuts, how many pounds of the higher grade peanuts ( at $ 4) should be used? Select one: O a. 20 pounds O b. 60 pounds O c. 40 pounds O d. 80 pounds