A. The maximum is achieved at the vertex of the parabola described by R(x). That will give you the value for x.
One way is to set the derivative R' = 0
The other way, since a parabola is axially symmetric with respect to the line through the apex, that is maximum of R occurs at x0 = (x1 +x2)/2, x1 and x2 are the roots of R. What are their values?
B. Evaluate R(x0)
c. Evaluate p(x0).
work out this problem first, then we see what next