As part of a survey, 16 adults were asked, "How many hours did you spend at your job last week?" The results are shown in the stem-and-leaf display below.

Number of hours worked last week

2 0 7
3 0 3 3 5 7
4 1 3 5 7 8 9 9
5 7 7

Key: 2|0 means 20 hours.

(a) What was the highest number of hours worked overall?
(b) What was the least number of hours worked in the 30s?
(c) How many responses fell in the 20s?