The answer would be:
$2.99 per undershirt.
Explanation:
The cost of the a pack of 6 is $13.98.
This is $3.96 less than 6 undershirts bought separately.
The amount is therefore: $13.98 + $3.96 = $17.94
So the individual prices is $17.94/ 6= $2.99 (DIVIDED BY 6)
HOPE THIS IS HELPFUL :))