Answer:
a) p = x/n
b) p = 2/5
c) see attached
Step-by-step explanation:
a) You apparently want to maximize L(p) with respect to p, assuming values of x and n are fixed. The derivative of L(p) can be found using the product rule. Then the value of p that maximizes L(p) can be found by setting the derivative to zero.

Setting this to zero, we have ...

b) For x=2, n=5, the likelihood function L(p) is maximized for ...
... p = x/n = 2/5
c) See the attached plot. The peak (maximum likelihood) is at p=0.4 = 2/5.
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Comment on the problem
This problem involves derivatives, something that you don't expect in a middle school math curriculum.