Let that certain number be 'n'
50% (n) = 39
50% ⇒ 0.5
0.5 (n) = 39
Divide both sides by 0.5
0.5n = 39
 /0.5    /0.5
n = 78.
So that certain number is actually <em><u>78! :)</u></em>
CROSS CHECK:
50% of 78
0.5 × 78
= 39
Hope this helps! :)
 
        
             
        
        
        
Answer:
the number --4
Step-by-step explanation:
-7--4=-3
-3--4=1
1--4=5
5--4=9
 
        
             
        
        
        
Fifty , 50 20+30=50, not sure if its asking much else
        
                    
             
        
        
        
Answer:
they each hike 2 miles
Step-by-step explanation:
Jeff: 15=1/2
         *4    *4
       60 min=2 miles
Lisa:  10=1/3
           *6   *6
         60 = 2
 
        
             
        
        
        
Answer:
1
Step-by-step explanation: