Sue, of Sue’s Sandwich Shoppe, sells sandwiches and sodas from a sidewalk cart in a popular park near her house. She sets up her cart in the summers to earn money for college tuition. Last month she sold $1,240 worth of product (sandwiches and sodas) to 100 customers. She spent $210 on the sandwich ingredients and buying the sodas wholesale. Her unit is one sandwich ($4) plus one soda ($1). Define the unit of sale and calculate the economics of one unit for Sue’s Sandwiches.