Alumber company combined oak wood chips that cost $3.40 per pound with pine wood chips that costs $2.60 per pound. how many pounds of each were used to make a 40-pound mixture costing $2.80 per pound?

Algebra: must make a chart

                  $/lb   *   # of lbs   =   total

Oak           3.4             x              3.4x

Pine           2.6          40-x        104-2.6x

Mixture      2.8           40               112

Now you can set up your equation ( assuming you know how to do equations 'cuz I figure you're in algebra)

3.4x + 104 - 2.6x = 112

.8x + 104 = 112

.8x = 8

10 pounds of oak

30 pounds of pine