My Gram's Peanut Butter Cookies

1 cup butter or margarine, softened
1 cup sugar
1 cup brown sugar, packed
1 cup peanut butter
2 eggs
1-1/4 tsp baking soda
1 tsp baking powder
2-1/2 cups flour
1/2 tsp salt

Combine all ingredients and mix well. Form into ball and place on ungreased cookie sheet. Press down with fork to flatten. Bake 15 minutes at 375.