A nursery sells Kentucky Blue Grass seed for $5.75 per pound and Tall Fescue seed for$4.50 per pound. The nursery sells a mixture of the two kinds of seed for$5.25 per pound. Let k represent the amount of Kentucky Blue Grass seed the nursery uses in 5 pounds of the mixture. Write an equation to represent the problem. How much Kentucky Blue Grass does the nursery use in 5 pounds of the mixture? How much Tall Fescue does the nursery use in 5 pounds of the mixture?

Question

see the coffee example, and the lima bean example.

http://www.purplemath.com/modules/mixture.htm

i still don't get it

is the equation k=m-TF