Ayayai Corp. makes and sells deck coating which is sold by the gallonTwo pounds of sand are needed to make one gallon of deck coatingBudgeted production of deck coating for the next two months follows: September $20,000$ gallons October $30,000$ gallons The company wants to maintain monthly ending inventories of sand equal to $20\%$ of the following month's production needsOn August $31,8,000$ pounds of sand were on hand. How much sand should be purchased in September $?$