angularjs two comboboxes bound to different models how can I get models that are selected

I want to have two combo boxes built based on an array of objects in angular.  One is bound to positions, the other is bound to transactions.  I want to select one row on each then click a button and pass each into a function.

Q: How can I pass the selected position and the selected transaction into a function when a user clicks a button?

<select size="10">
<option ng-repeat="transaction in transactions" value="{{transaction.id}}">{{transaction.symbol}}</option>
</select>  

<select size="10">
<option ng-repeat="position in positions" value="{{position.id}}">{{position.title}}</option>
</select>

<button ng-click="?????????">

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