A hardware store want to mix sand worth $8 per pound with sand worth $4 per pound to get an 80 pound mixture that is worth $5 per pound. How many pounds of each type of sand should be used?

Which lines are parallel? justify your answer. lines p and q are parallel because same side interior angles are congruent. lines p and q are parallel because alternate exterior angles are congruent lines l and m are parallel because same side interior angles are supplementary lines l and m are parallel because alternate interior angles are supplementary.