A retailer buys goods from the manufactures and wholesalers and then sell these products directly to the consumers or users.In the supply chain retailers are the ones who connect with the customers to obtain information on goods and servicers delivered.
So first you would divide 3,600 by 420. You should get the answer of 8. Then multiply 8 by 12 to get the total number of gallon needed, which is 96 gallons.