B because I’m just guessing
She sold 60% of her cookies.
This is a proportional problem.
The distance 'd' corresponds to the 9 inches.
The 7-ft pin corresponds to the size 's'.
Convert 7ft to 7/3 yds. This way you have equal ratio of yds to inches.
Given:
The logarithmic expression is:

To find:
The equivalent expression of given expression by using change-of-base formula.
Solution:
The change-of-base formula is:

The given expression is:

Using the change-of-base formula, we get

Where, is a constant and c>0.
Let
, then

Therefore, the correct option is a.