10 is a common factor of 50 30 and 100. So is 2
        
                    
             
        
        
        
Your answer correct good night
 
        
        
        
Well first off if you have a negative sign in front of the seven, DO NOT have a plus sign because it will be confusing. So y-7=13? , You add 7 to 13 and = 20, so y= 20
        
             
        
        
        
Answer: 
5/8
explanation: 
5/4(2)=10/8-5/8
        
             
        
        
        
+1/31 and -1/31
Hope this helps.