By Green's theorem,

where
is the circle
and
is the interior of
, or the disk
.
Convert to polar coordinates, taking

Then the work done by
on the particle is

Presuming the question is "How many points did he miss", you would find the solution by multiplying the amount of possible points by the test score as a fraction. 96% is the fraction

. Therefore, you get the equation

. This is equal to 72, so he missed 3 points, or 75-72 points.
He missed 3 points.
Letter c is an operation.
Addition