Add model values based on condition inside ng-repeat

Binding an object MyLanguageSkills which has (properties)

Writing  - number
Speaking  - number
Name  - text

The object is bound to UI like below

<tr ng-repeat="myLanguageSkill in MyLanguageSkills">
 <td>
  <input name="Writing"  type="number" ng-model="myLanguageSkill.Writing">
</td> 
 <td>
  <input name="Speaking"  type="number" ng-model="myLanguageSkill.Speaking">
</td> 
<td>
   <input name="CandidateName"  type="text" ng-model="myLanguageSkill.CandidateName">
</td>
</tr>

If someone types, more than 10 in first “Writing” input text box, then the rest above 10 should be added to “Speaking” input textbox and also Speaking should not accept more than 10 by itself.

For example:

Writing 11
Speaking 2

Then 

Writing 10
Speaking 3

I am not sure how to make the ng-change happen for the above scenario, as this deals with models inside a repeat loop ? any help will be appreciated.

Source: AngularJS