我是Java初学者现在正为一道题目难倒，放情哪位高手达人帮忙解答。题目如下：
For this program, assume you have an input file with several lines of text. Each line has a student's last name, followed by a space and then 4 numbers which represent his/her grades. Your program should read this input file and produce an output file with the same number of lines, each line showing the last name and the average of the student's scores.
Before.....
$ cat grades.txt
Bush 50 70 75 80
Clinton 85 90 95 98
Gore 90 95 98 97
Cheney 80 90 95 85
Powell 90 95 85 99
Lieberman 85 95 90 94
after......
$ cat gradeAvg.txt
Here are the average grades:
Bush 68.8
Clinton 92.0
Gore 95.0
Cheney 87.5
Powell 92.2
Lieberman 91.0
先这里谢谢了！！！！