What should you use if a chocolate cake recipe calls for bouth baking soda and baking powder but you only have baking powder?

If you only have baking powder and a recipe calls for both baking soda and baking powder, you can generally replace the baking soda with additional baking powder. For every teaspoon of baking soda needed, use about 2 to 3 teaspoons of baking powder, but keep in mind that this may alter the cake's texture and flavor slightly. Additionally, since baking powder already contains an acid, you may want to adjust the recipe by reducing any additional acidic ingredients.