Answer: Xn = n(n+1)/2
Step-by-step explanation:
Firstly, you work with asingle dot for each and let n= 1,2,3,4....
Now if you double the dots, it will form a rectangle and it is easier to work with many dots i.e just multiple n by n+1
Dots in rectangle= n(n+1)
But remember the number of dots were doubled therefore, 
Dots in triangle = n(n+1)/2.
 
        
             
        
        
        
Set up proportions
8/28=5/21
8*21=168
5*28=140
so no, they are not equivalent
        
             
        
        
        
49 is the answer cjfuvvryssokskdoxofo
        
             
        
        
        
Answer:
B
Step-by-step explanation:
because the numbers 0-9 consist of 10 numbers,
having a 70% chance of success means that out of the 10 numbers, 7 are correct.
thus, choice B is correct as it have 7 numbers in it
(rmb to count "0" as a number!)
 
        
                    
             
        
        
        
Answer:
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