```
public function add($temp) {
        $newNum = $this->num + $temp->num;
        if($this->denum == $temp->denum) {
               // add two fractions having same denominator
               $answer = $newNum . "/" . $this->denum;
        } else {
               // how to add two fractions having different denominator?
        }
        return $answer;
}

```

In other words, how to handle the case of two fractions having different denominators, like:

> 
> 1/3 + 1/6 = 3/6
> 
> 
> 

or

> 
> 1/3 + 1/5 = 8/15
> 
> 
>