Answer:
10
Step-by-step explanation:
 
        
             
        
        
        
so first day and so on
7, 10, 13,....
as you can see it's an arithmetic progression 
so sum for nth term= n/2 { 2a + (n-1) d}
 it's the sum of the 7th term
 so 
7/2 { 7 ×2 + ( 7-1) 3}
7/2 × 32
7× 16
112 fishes
 
        
                    
             
        
        
        
Answer:

perform cross multiplication:
