Nancy went on vacation and sent postcards to all of her family and friends. She needed 39 postcards, but the store only sold them in packs of 15. She bought 3 packs. How many postcards did she have left over?

Asmall business produces and sells balls. the fixed costs are $20 and each ball costs $4.32 to produce. each ball sells for $8.32. write the equations for the total cost, c, and the revenue, r, then use the graphing method to determine how many balls must be sold to break even.