Tuna And Olive

• 14 marinara
• 170 gr spaghetti (cooked)
• 50 gr onion (minced)
• 34 gr greek olives (sliced)
• 30 ml olive oil
• 7 gr parsley (chopped)
• 3 gr garlic (minced)
• 1 gr salt
• 1 gr pepper
• 1 package oil-packed italian tuna