The cost of coffee is determined by the type of coffee beans that are mixed together. the cost of of a local mix of a arabica and robusta beans is modeled by the equation below where a equals 2 pounds of arabica and r= pounds of robusta 700a + 1200r =1,000,000 if a mixture contains 1000 pounds of arabica how many pounds of robusta beans should be in the mixture? r= pounds numerical answer !