1. Preheat oven to 375°.
2. Peel, core, and slice the apples into a bowl.
3. Add lemon juice and sugar.
4. Pour into a greased shallow baking dish (8 or 9 inches).
5. Combine the oatmeal, brown sugar, flour, cinnamon, and salt.
6. Cut in the margarine with a pastry blender.
7. Sprinkle over the apples.
8. Bake for about 30 minutes, or until apples are tender.
9. Serve hot, warm or cold.