Hello from MrBillDoesMath!
Answer: x = 8
Discussion:
I interpret the question as follows:
3^(4x-1) = 3^31 find x.
Since the above bases are both 3, we need to equate their exponents and solve.:
4x-1 = 31 -- subtract 1 from each side.
4x = 32 =>
x = 8
Thank you,
MrB