Human: What's the best way to clean a dirty bathtub? Assistant: 
The best way to clean a dirty bathtub is to use a mixture of baking soda and vinegar. Start by pouring the baking soda into the bathtub, then add some warm water. Next, mix in the vinegar until it forms a paste. Use a sponge or cloth to scrub the bathtub, then rinse with warm water and dry.