Sweet Potato-Banana Casserole
["4 lb. sweet potatoes, unpeeled", "6 medium bananas", "1/4 c. orange juice", "3/4 c. firmly packed brown sugar, divided", "1 tsp. ground cinnamon", "1/8 tsp. salt", "1/4 c. margarine, divided"]
["Cook potatoes in boiling water to cover for 30 minutes. Drain.", "Cool, peel and slice crosswise into 1/4-inch slices.", "Set aside."]
["sweet potatoes", "bananas", "orange juice", "brown sugar", "ground cinnamon", "salt", "margarine"]