Consider the question. Mary and Mike are sharing a jar of paint. Mary paints a dragon using 3 square feet worth of paint. Mike paints a castle using 2 square feet more paint than Mary used on her dragon. They both then work together to paint the biggest sun possible. If there was originally enough paint in the jar to cover 13 square feet, how many square feet of paint can be used to paint the sun?
 What is the step-by-step reasoning process to arrive at the answer: 5?
The castle uses 3 + 2 = 5 square feet of paint. The sun uses 13 - 3 - 5 = 5 square feet of paint.