Happy New Year from MrBillDoesMath!
Answer:
n = log(76/25) / log(5)
Discussion:
5^n -3 = 1/25 => (add 3 to both sides)
5^n = 3 + 1/25 = 73/25 + 1/25 = 76/25 (take log;s of both sides)
log(5^n) = log (76/25) =>
n log(5) = log(76/25) =>
n = log(76/25) / log(5)
Thank you,
MrB