Find the largest number among the following expressions: \(30^{30}\), \(50^{10}\), \(40^{20}\), \(45^{15}\), and \(5^{60}\). The original answer is in the form a^b, where a is the base and b is the exponent. Please provide the sum of a and b.

Let's think step by step and output the final answer within \boxed{}.
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