Mixture Problems are problems where two (or more) parts are combined into a whole. They can be solved using weighted averages.
Imagine that red marbles sell for $2.00 a pound, and blue marbles sell for $1.00 a pound. You have 10 pounds of red marbles. How many pounds of blue marbles should be mixed in to create a mixture worth $1.40 a pound?
Using the totals, we can arrange the equation to solve for "x":
20 + x = 1.40(10 + x)
20 + x = 14 + 1.4x
6 = 0.4x
15 = x
It would take 15 pounds of blue marbles to create a mixture worth $1.40 a pound.