how to delete a line from the file

Shell Programming and Scripting
1

Hi,
I have a file which contains entries with different numbers, for example:

275|24hroff|sel,fill,dbw|
2758|24hroff|sel,fill,dbw|
2765|24hroff|sel,fill,dbw|
2920|24hroff|sel,fill,dbw|

I need to delete a line which contains certian number, for instance 275
I was trying to use 'sed' but it removes all lines containing this pattern, so line with number 275 and 2758 are removed. I need to remove the exact match only. Also, number is an argument in my script. For example, PX=275
May be somebody come across a similar problem. I am in ksh88
Thanks a lot for any help -A

2 
sed '/^275\|/d' inputfilename
3 
> cat file90
275|24hroff|sel,fill,dbw|
2758|24hroff|sel,fill,dbw|
2765|24hroff|sel,fill,dbw|
2920|24hroff|sel,fill,dbw|
> grep -v "275|" file90
2758|24hroff|sel,fill,dbw|
2765|24hroff|sel,fill,dbw|
2920|24hroff|sel,fill,dbw|

Or, with a variable...
Note that $PX equals ${PX} ; just more explicit when other characters also in the data stream.

> PX=275
> grep -v "$PX|" file90
2758|24hroff|sel,fill,dbw|
2765|24hroff|sel,fill,dbw|
2920|24hroff|sel,fill,dbw|
> grep -v "${PX}|" file90
2758|24hroff|sel,fill,dbw|
2765|24hroff|sel,fill,dbw|
2920|24hroff|sel,fill,dbw|
4 
grep -vw $var file.txt