15kg of bronze was made by combining 10/kg of copper which costs $3/kg with 5kg of tin which costs $9/kg. Find the cost per kg of the mixture.

The number of calories you burn depends on your weight. a 110-pound person burns 163 calories during 30 minutes of tennis. find the number of calories that a 190-pound person would burn during the same activity, assuming they burn calories at the same rate.