He would most likely be referring to kilometers if it is a large area. So D would be your answer.
I'll assume you're supposed to compute the line integral of 
over the given path 
. By the fundamental theorem of calculus,
so evaluating the integral is as simple as evaluting 
at the endpoints of . But first we need to determine given its gradient.
We have
Differentiating with respect to 
gives
and we end up with
for some constant . Then the value of the line integral is 
.
(2+5x)=(4x+7)
-4x on each side
-2 in each side
x=5
An angle is the intersection of two noncollinear rays at a common endpoint. The rays are called sides and the common endpoint is called the vertex.
By multiplying both sides of an equation by a number, you can eliminate all decimals and fractions, so the answer is C.
