Question: Clean a hairbrush.
Option 0: You will need an old toothbrush, dish detergent and hot water. Add detergent to hot water and soak hairbrush. Once brush is wet, use an old toothbrush to clean the bristles. Let dry on towel.
Option 1: To clean an old toothbrush you will need dish detergent, hot water and a brush.  Add detergent to hot water and soak tooth brush. Once toothbrush is wet, use an old hairbrush to clean the bristles. Let dry on towel.
Answer: 0