a new blend of coffee will cost $3.90 per pound by mixing 2 coffees that sell for $2.75 and $5 per pound. what amounts of each coffee should be blended to obtain the desired mixture?

Question

a new blend of coffee will cost $3.90 per pound by mixing 2 coffees that sell for $2.75 and $5 per pound. what amounts of each coffee should be blended to obtain the desired mixture? 
(the total weight of the desired blend is 100 lbs)

How would I solve this? 
The equation would 3.90 = 2.75x + 5x ? 
3.90(100) = 2.75x + 5x

drwls · Answer

Let there be x lb of the expensive coffee and y lb of the inexpensive coffee.

x + y = 100

5x + 2.75 y = 3.90*100 = 390

Now solve for both x and y.
5x + 5y = 500
2.25 y = 110
y = 48.89
x = 51.11

It is almost a 50/50 blend