Question

how many pounds of coffee worth $10 a pound should be added to 20 pounds of coffee worth $4 a pound to get a mixture worth $5 a pound

Answer 1

4

Explanation:

1. if the mass of coffee worth $10 is 'x', then its worth is 10x, and the worth of the mixture is 5(x+20);

2. using the previous item it is possible to write the next equation:

5(x+20)=4*20+10*x; ⇒ x=4.

3. the required mass is 4 pounds.