Hi @udapud
I think your field names are incorrect. Perhaps you could post a screenshot of the field group edit page so I can see the repeater / sub fields
Also, a screenshot of the edit page would be good.
As for the 75 sub fields, this is most likely due to 1 of 2 things:
1. You have selected a minimum of 75 rows for the repeater field
2. You have a previously saved value with the same field_name. This would have saved the value 75 at some point