Rhubarb Dessert

4 - 5 cups rhubarb
1/2 cup white sugar
3/4 cup brown sugar
3 Tbsp flour
3/4 cup quick oatmeal
3/4 cup flour
3/4 cup brown sugar
1/4 tsp baking soda
1/4 tsp baking powder
1/3 cup margarine

Place first four ingredients in a 9" x 13" cake pan - stir together. Melt margarine and mix with remaining ingredients. Crumble on top and bake at 350-375º oven until it bubbles through the topping, approximately 45-55 minutes.