Auto Expiry Date Calculation based on Shelf life and Date of Manufacture

Hi All

this is my first time asking for help

i am working on a form where there are 3 fields in the acrobat form

1. mDate

2. sLife

3. eDate

sLife is an autopopulated field reflecting shelf life in number of months. e.g 12, 24, or 36

mdate is user entered reflected in dd/mm/yyyy

I am trying to make ExpiryDate field automatically calculated

Is there a way to calculate? Thanks for your help

kind regards

Salma