According to the law of conservation of Mass:
In a chemical reaction mass can neither be created nor be destroyed
So, we can say that: Mass of A + Mass of B = Mass of C
In the given reaction, 
One of the reactants weigh 5 grams and another one weighs x grams
The mass of the product of this reaction is 9 grams
<u>Mass of reactant B:</u>
Mass of A + Mass of B = Mass of C
5 + x = 9 
x = 4 grams
 
        
             
        
        
        
I cannot see the whole equation.Therefore I shall not answer
        
             
        
        
        
Explanation:
conduction involves the transfer of molecules due to the movement of particles