To get a number to decrease by 21% you multiply it by 0.79 (1-0.21)
r = 0.79
        
                    
             
        
        
        
To find what 25 percent of 130 is we must convert 25 to a decimal. 0.25
Then we multiply .25 and 130 to get 32.5 dollars off 130. This means that the radio and earphones will cost $97.50 and you will have $2.50 remaining. 
If this helped you out Brainliest answer would be appreciated
        
                    
             
        
        
        
Answer:
12/16 = 3/4
I divided both sides by 4.
Hope this helps!
-Mikayla