Refer to Exercise 5.69. Use the complementation rule to find the probability that a randomly selected senator

Question:

Refer to Exercise 5.69. Use the complementation rule to find the probability that a randomly selected senator in the 109th Congress is
Age (yr) No. of senators
Under 50 ........... 12
50–59 ........... 33
60–69 ........... 32
70–79 ........... 18
80 and over .......... 5
a. 50 years old or older.
b. Under 70 years old.