Determine the critical region and critical values for z that would be used to test the null

Question:

Determine the critical region and critical values for z that would be used to test the null hypothesis at the given level of significance, as described in each of the following:
a. Ho: µ = 20, Ha: µ = 20, a = 0.10
b. Ho: µ = 24 (≥), Ha: m_24, a = 0.01
c. Ho: µ = 10.5 (≤), Ha: m_10.5, a = 0.05
d. Ho: µ = 35, Ha: µ = 35, a = 0.01