关于#python#的问题：请用Python解答

Question

如图所示，请用Python解答，最好加一点注释，第三和第四题

Answer 1

a = {'张三':45,'李思':78,'王吴':40,'周六':96,'赵琪':65,'孙霸':90,'郑九':78,'吴诗':99,'董世义':60}
ages = [a[k] for k in a]
mx = max(ages)
mn = min(ages)
avg = sum(ages) / len(ages)
grade = 'abcde'[::1]
print('最高分：{}，最低分：{}，平均分：{}'.format(mx,mn,round(avg,1)))
for k in a:
    print('{} 成绩为 {}'.format(k,grade[a[k] // 20]))

a = [3,7,1,23,45,21,12]
b = (0,2,33,55,11)
a += b
n = int(input())
if a.count(n) > 0:
    print(a.index(n))
else:
    print('n is not find')