Ubuntu :: Calculations In A Shell Script?

I'm having some troubles with my backup script, i want to delete the folder that is 2 weeks old. The problem is that when is use the folowing code:

YEAR=(date +%Y)

Code:

#Remove old directories
TWOWEEKSAGO=$(date +%U)-2|bc
echo $TWOWEEKSAGO
#rm -r /home/[my home directory]/Backups/$YEAR/$TWOWEEKSAGO/

The $TWOWEEKSAGO variable is [empty] and not 14, but when I remove the -2|bc and I use:

Code:

echo $TWOWEEKSAGO-2|bc

It echo's 14.the weeknumber at this moment minus 2, I have to fix it when the weeknumber is 1 or 2 so the directory of the last year will be deleted, but I will fix that later if you don't know that.

Code:

#Remove old directories
TWOWEEKSAGO=$(date +%U --date='2 weeks ago')
rm -r /home/[my home directory]/Backups/$YEAR/$TWOWEEKSAGO/

After 30 minutes with some help I coded the following to delete the folders of last year:

Code:

#Remove old directories
TWOWEEKSAGO=$(date +%U --date='2 weeks ago')
if [ $TWOWEEKSAGO -eq 51 ]; then

[code]....