Let:
x = Chemistry textbooks sold
y = Physics textbooks sold
The textbook store sold a combined total of 260, so:

The number of chemistry books sold was three times the number of physics textbooks sold, so:

Let:

Replace (2) into (1):

Replace the value of y into (2):
 
 
        
             
        
        
        
Answer:
The answer is 19305
Step-by-step explanation:
 
        
             
        
        
        
Answer:

Step-by-step explanation:
Let's try guessing...

All the units place has to be 4, if it is higher than 4 then the answer will not be 90 (the sum of the four rounded numbers).

 
        
             
        
        
        
There are 14 possibilities for first place.
There are 13 possibilities for second place, since a dog can't get both first and second place.
There are 12 possibilities for third place, since a dog can't get both first, second, and third place.
There are 11 possibilities for fourth place, since a dog can't get both first, second, third, and fourth place.
Multiply them together and get 24024 possibilities.
Hope this helps!
        
             
        
        
        
Answer:6/36
Step-by-step explanation: