Question 12859
First lets choose a variable for the three unknown numbers. They are consecutive which means that they are in ascending(going up)order (for example..1,2,3,4)

So Lets choose X for the first number.
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since the next number is consecutive to X, it will be one number more than X which is written as X+1
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So, Let the second number = X+1 (that is just the first unknown number plus 1)
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now the next nuber is still consecutive so it's just X+1+1 OR simplify to X+2
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NOW, to recap, our unknown numbers are:
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 X
(X+1)
(X+2)
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and we know that the sum of these three numbers is equal to 600.
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so write as:           X+(X+1)+(X+2)=600

Simplify:                       3X+3=600
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Get the x on one side by subtracting 3 from both sides:      
                                  3x+3=600
..                                     -3=-3         
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.After that it becomes: 3x=597
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Now, get the X by itself by dividing both sides by 3:
                           3x=597 
 ..                           X=199

 now you know x, so plug it in   X=199
                                 X+1 is the same as 199+1 which is =200
                                 X+2 is the same as 199+2 which is 201

so the answers are: 199, 200, 201
they are consecutive and the sum of the three is =600

I hope this helps. =)