Answer:
C. 15
Step-by-step explanation:
The following proportional can be set-up for the figure given:

Solve for x


Cross multiply


15 = 6x - 5x
15 = x
x = 15
Answer: -n-4
Step-by-step explanation:
Distribute the - to n and 4
It would have to be letter D my guy, if you know what centuries and decades are this is easy
3x-6=21
Or,3x=27
Or,x=27/3
Or,x=9
So,Now,
X-2=9-2
=7
Hope it helps