Young girl using phone to check in airport before boarding. Credit: KSChong / Getty Images Many national and international airlines offer fare discounts for students and young adults, as well as perks like increased bag allowances and flexible flight change policies.Although eligibility varies by airline, qualified fliers are usually between the ages of 16 and 30, and need to show proof of being a student, like a valid school ID.While most discounts are in the 10 to 15 percent range, some carriers, like Scandinavian Airlines, offer discounts up to 70 percent. Who doesn't love saving money on travel? Students and young adults, in particular, are often looking for ways to save due to limited budgets, and luckily, there are plenty of options. With that in mind, before booking your next flight, it's a good idea to check if your airline offers any student or young adult discounts, which can range from five percent to up to 70 percent, depending on the airline and cabin class.…