Your answer would be 9^13
        
             
        
        
        
Given that,
The camera sights the stadium at a 7 degree angle of depression. 
The altitude of the blimp i slide 300 m.
To find,
The line of sight distance from the camera to the stadium.
Solution,
If we consider a right angled triangle. Let x is its hypotenuse i.e. the line of sight distance from the camera to the stadium. Using trigonometry :

So, the line of sight is at a distance of 2461.65 m from the camera to the stadium.
 
        
             
        
        
        
Well since there are more Yellow balloons there is a less chance of it getting picked twice because there other colors. 
So it will probably be 7 over 15
 
        
             
        
        
        
3x-13=305
3x=305+13
3x=318
(3x)÷3=318÷3
x=106
check.. (3×106)-13=305
318-13=305
305=305