Answer:
C. 6
Step-by-step explanation:
It is given that the rectangles in the figure are similar.
<em>Thus, the corresponding sides of the two rectangles will be equal.</em>
So, we get,

i.e. 
i.e. 
i.e. 
i.e. x = 6.
Hence, the value of x is 6.
Recall the logarithm rules :
a^y = x is the same as log_a x = y
In this case,
a = 18
y = r - 10
x = 93
So,
18^ (r-10) = 93
is the same as
log_18 93 = r - 10
Solve for r to get :
10 + log_18 93 = r
Pretty sure the answer is d brodie