Class : Class 7 
                                                                                                        
                                                                                                        C is the answer as:- 
Assume that tank p as x and tank q as y. 
We know that:-
X=3y
X+y=60 litres
And the question is:-
What is the value of x if x=3y and x +y =60 ?
It is 15 as x+y =4x and 4x=60 and x=60/4= 15
So,15 litres should be poured from tank p to tank q.
                                                                                                    
                                                                                                     
             
             
         
                                                                         
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
