Factored form: (x-5)(7x+5) ☺
        
             
        
        
        
63 + 36...there is a common factor of 9
9(7 + 4) <== this is equivalent
63 + 36...there is a common factor of 3
3(21 + 12)...but this is not an answer choice...but it is equivalent
        
             
        
        
        
Answer:
9.245
Step-by-step explanation:
6 + 3.245 = 9.245
 
        
                    
             
        
        
        
Answer:
The miner would have 3 1/2 of radioactive material in the sample at the beginning of the 7th day.
Step-by-step explanation:
hope this helped!