Chocolates costing $8 per pound are to be mixed with chocolates costing $3 per pound to make a 20 pound mixture. if the mixture is to sell for $5 per pound, how many pounds of each chocolate should be used?

Hello,

Let's assume
x the number of pounds of chcolates costing $8/pound
y the number of pounds of chcolates costing $3/pound

If profits =0
 x+y=20==>y=20-x
 8*x+3*y=5*(x+y) ==>8*x+3*(20-x)=5(x+20-x)
==>8x+60-3x=100
==>5x=40
==>x=8 and y=20-8=12

Remark:
If we use less chocolates costing $8/pound we will make more profits.