Preheat your oven to 350 degrees Fahrenheit. Grease a loaf pan with cooking spray or butter.

In a large bowl, mix together flour, baking powder, baking soda, and salt. Set it aside.

In a separate bowl, cream together the margarine and sugar until light and fluffy. Add in eggs one at a time, mixing well after each addition.

Mash the bananas and add them to the wet ingredients along with lemon juice. Mix well.

Gradually add the flour mixture to the wet ingredients, mixing until just combined. Do not overmix.

Fold in the chopped nuts into the batter.

Pour the batter into the greased loaf pan and smooth out the top with a spatula.

Bake for an hour or until a toothpick inserted in the center comes out clean. If the bread starts to brown too quickly, cover it loosely with foil.

Let the bread cool in the pan for 10 minutes before removing it and placing it on a wire rack to cool completely.

Slice and serve the bread or store it in an airtight container for up to 3 days. You can also freeze it for longer storage.