As you are using jQuery / JavaScript and if you don't want to write a complex code. Then I will suggest easiest steps for this.
Step 1: When rendering question in view: Place integerOne in one placeholder, operator in another placeholder and integerSecond in another.
Example: <div class="row" id="row-1"><span class="intOne">{integerOne}</span><span class="operator">{operator}</span><span class="intSecond">{integerSecond}</span></div>
Step 2: Bind this Div with your calculate button
Step 3: On Click of calculate button, read integers and operator from PlaceHolders and do case calculation as j has mentioned below.
This is just easiest way for solution, maybe once it start working you can polish it with more robust code.