Answer:
The answer is 9
Step-by-step explanation:
take 4 to the other hand it become -4 
 
r=13-4=9 
 
        
             
        
        
        
Answer:
5 apples 
Step-by-step explanation:
4 friends + Robby = 5 people
25 apples in total ÷ 5 people 
= 5 apples per person
 
        
             
        
        
        
1. Number that adds up to -12 and multiplied by the same # that gives u -13. Set it up like this because both are negative so, u need 1 negative and 1 positive.
(x-13)(x+1)
2. Same rule applies. GCF
8y(4y+1)
3. (x+3)(x-3)
        
             
        
        
        
8/4=12/x 
Would be the ratio. 
Solve it: 
8/4 =12/x 
2=12/x
2x=12
X=6