Regine Joy G. Memes Shanmie O Cetar Aicen C Cañete • Mariel is buying the following school items at a bookstore's back-to-school sale Notebook: Go (20% off) Balpen Set: PRO (10% Off) Backpack: $850 (25% off) Questions: C. Calculate the total discount for all items. b. Determine the final amount Mariel pays- inclusive (129.