Consider the question. Mikaela was repainting her bathroom. She bought 16 containers of paint to cover the four equally-sized walls. At the last minute, she decided to put tile on one wall in the bathroom and paint flowers on the ceiling with one container of paint instead. How many containers of paint will she have left over?
 What is the step-by-step reasoning process to arrive at the answer: 3?
Mikaela would use 16 / 4 = 4 containers of paint per wall. To paint 3 walls, she will use 3 * 4 = 12 containers. After using 1 container for the ceiling, she will have 16 - 12 - 1 = 3 containers of paint left over.