C
If you plug in the values in that equation, it works.
Answer:
we need to prove : for every integer n>1, the number
is a multiple of 5.
1) check divisibility for n=1,
(divisible)
2) Assume that
is divisible by 5, 
3) Induction,



Now, 



Take out the common factor,
(divisible by 5)
add both the sides by f(k)

We have proved that difference between
and
is divisible by 5.
so, our assumption in step 2 is correct.
Since
is divisible by 5, then
must be divisible by 5 since we are taking the sum of 2 terms that are divisible by 5.
Therefore, for every integer n>1, the number
is a multiple of 5.
The answer is 2.7
I’m not an expert at this but i did some research so I hope I can help
It’s 2.7 because the formula for calculating density is to divide the mass by the volume and in you do that for each of them you get 2.7 every time
X=y-2
2y=5x-17
Substituting for x into the second equation, we find
2y=5(y-2)-17
2y=5y-10-17
-3y=-27
y=9
So x=7
Thus, the two numbers are 7 and 9.