Mcdonalds sells quarter-pound cheeseburgers for .99 cents last saturday. they sold 310 of these cheeseburgers. how many pounds of cheese did they sell last saturday?

The first thing you should do is calculate how many pounds of cheese a hamburger has
 1 hamburger = 1/4 pound of cheese.
 Then, you can make a rule of three to know how many pounds of cheese were sold:
 1 ---> 1/4
 310 ---> x
 Clearing x we have:
 x = ((310) / (1)) * (1/4) = 77.5
 Answer
 they sell last saturday 77.5 pounds of cheese

The graph isn’t that clear