Question

The cost of coffee is determined by the type of coffee beans that are mixed together. The cost of a local mix of Arabica and Robusta beans is modeled by the equation below, where A = the pounds of Arabica and R = pounds of Robusta:

700A + 1200R = 1,000,000

If a mixture contains 1000 pounds of Arabica beans, how many pounds of Robusta beans should be in the mixture?

R = ________________ pounds

Answer 1

Substituting 1000 for A, we have 1200R+700,000=1,000,000.  Subtracting 700,000 from both sides, we have 1200R=300,000.  Dividing by 1200, we see that R=250.