Answer:
a) Null hypothesis:

Alternative hypothesis:

b) Null hypothesis:

Alternative hypothesis:

c) Null hypothesis:

Alternative hypothesis:

Explanation:
A hypothesis is defined as "a speculation or theory based on insufficient evidence that lends itself to further testing and experimentation. With further testing, a hypothesis can usually be proven true or false".
The null hypothesis is defined as "a hypothesis that says there is no statistical significance between the two variables in the hypothesis. It is the hypothesis that the researcher is trying to disprove".
The alternative hypothesis is "just the inverse, or opposite, of the null hypothesis. It is the hypothesis that researcher is trying to prove".
Based on this we can answer the question.
Part a
The system of hypothesis for this case would be:
Null hypothesis:

Alternative hypothesis:

Would be a upper right tailed test on this case.
Part b
The system of hypothesis for this case would be:
Null hypothesis:

Alternative hypothesis:

Would be a two tailed test on this case.
Part c
The system of hypothesis for this case would be:
Null hypothesis:

Alternative hypothesis:

Would be a lower left tailed test on this case.