#### Answer

7 lbs

#### Work Step by Step

We have 14 lbs of 4 dollars/lb coffee, and want to add 7 dollars/lb coffee until the value adds up to 5 dollars/lb.
7x + 4(14) = 5(x + 14)
Simplify:
7x + 4(14) = 5x + 5(14)
7x + 56 = 5x + 70
2x + 56 = 70
2x = 14
x = 7