Answer:
d = log 38/log31
d = 1.06
Explanation:
31 ^ d = 38
Take log of both sides since the exponential equation have different base (always)
d log 31 = log 38
d = log 38 / log 31
d = 1.58 / 1.491
d = 1.06.
We can actually check to see if this is correct.
Substituting d = 1.06
31^ 1.06 = 38.092
(You see, that's approximately correct)
Keep learning, maths is fun!