You went wrong on the rule of logarithms that says



You move the entire exponent in front of the log:




Take logs of both sides



Now use the rule that you missed.  Move the
(d-4) in parentheses in front of the log on
the left, and move the (3-d) in parentheses 
in front of the log on the right, and 
get:



Now here is something that might make it
easier for you, since it is easier to work
with single letters than logs.  So I suggest
doing this:

Let the letter A = log(16)
Let the letter B = log(3)

Substitute the letter A for log(16) and
substitute the letter B for log(3)













Now get your calculator and find

A = log(16) = 1.204119983
B = log(3) = .4771212547

Substitute those:





Edwin