First we have to find derivative of f(x):

For x=2 we have:

Now, 
Hence, the answer is A) 2
64+67 equal 131 subtract that from 180. You will get 49. :)
From the second equation we can find that d=43-(9/10)*n
we can put this equation into the first one,
So we have equation 60(43-(9/10)*n)+65n=2800
Solving that we get n=20
60d+65*20=2800
d=25
So the answer is d=25 and n=20
You have to find the slope and where it intercepts at