Answer:
702 emails
Step-by-step explanation:
<h2>This problem bothers on depreciation of value, in this context it is Joe's email that has depreciated by 10%.</h2>
Given data
Average personal emails received monthly = 
Average work emails received monthly
We are required to solve for the new amount of emails Joe will be receiving after changing his address, to find this value we need to solve for the depreciation of his personal mails.
After solving for the depreciation , we then need to subtract the depreciation from the initial number of mails to get the new number of mails.
let us solve for 10% depreciation.

The new number of mails

Joe will be receiving an average of 702 emails in his personal account monthly