Answer: 9^10
In other words, n = 10
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You use the rule (a^b)^c = a^(b*c) which says to multiply the exponents whenever we raise some exponential to some other exponent.
In this case, a = 9, b = 2, c = 5
(a^b)^c = a^(b*c)
(9^2)^5 = 9^(2*5)
(9^2)^5 = 9^10