I have baking powder and not any baking soda to make snickerdoodles ?

and i know that 2 tablespoons and 1 teaspoon of cream of tarter make baking power but i want to know how i can use baking powder instead because i have no baking soda. on my recipe it says 1/4 teaspoon of baking soda and 1/4 cream oft tarter. and i dont know how i can use baking powder instead of the two.