the screen is black what's the question?
 
        
             
        
        
        
-13+9=-4
When you add a positive number to a negative number the answer will get closer to 0 and then progress up in positive numbers. In this case we are finding which of the numbers equals -4 when added to -13. Remember, if you add a negative to a negative you will get a negative.
-13+-17=-30 This is the wrong answer.
-13+-9=-21 This is the wrong answer.
-13+17=4 This is the wrong answer. (This is positive 4 we are trying to find -4)
-13+9=-4 This is the right answer
Therefore X=9
        
             
        
        
        
Somebody can estimate the length of a book by using a ruler and rounding it to the nearest whole number.
        
                    
             
        
        
        
5/6 of the boys brought their lunch. 
In order to determine the answer you need to divide 5/9 by 2/3 in which will give you 5/6.