You're confusing length and format.
The question is "What is the format for the variable name in the dataset both?"
$20 is the Length.
Neither datasets have a "Format" of $20.
The two options are
Dataset Variable Format
Employee name $10.
Sales name $15.
So in the merge, the first table read in is the 'Sales' table where the variable 'name' is formatted $15. so the new table has the variable 'name' formatted as $15.
Hope this helps.