Answer:
The amount of oil was decreasing at 69300 barrels, yearly
Step-by-step explanation:
Given


Required
At what rate did oil decrease when 600000 barrels remain
To do this, we make use of the following notations
t = Time
A = Amount left in the well
So:

Where k represents the constant of proportionality

Multiply both sides by dt/A


Integrate both sides


Make A, the subject

i.e. At initial
So, we have:






Substitute
in 

To solve for k;

i.e.

So:

Divide both sides by 1000000

Take natural logarithm (ln) of both sides


Solve for k



Recall that:

Where
= Rate
So, when

The rate is:


<em>Hence, the amount of oil was decreasing at 69300 barrels, yearly</em>
D cause that’s the answer
So 20% of $1,080 is 216.
1080 - 216 is 864
8% of 864 is 69.12
864 + 69.12 would be $933.12
B) residual value I think I'm sorry if I'm wrong I'm not 100% sure.. it's just a guess