Question 1173029
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Hello, your task is to construct an equation, right ?


Your equation should be 


   +-------------------------------+
   |    Emilie = Jordan.    (*)    |
   +-------------------------------+


(simply because it CAN NOT be nothing else).



So, let x = # of marbles Chloe has.


Then Emilie has  2x + 7 marbles (from the condition),

     Jordan has  3x - 15 marbles.



Thus your equation (*) takes the form


    2x + 7 = 3x - 15.


Solve it using basic Algebra;  then complete the solution on your own.
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At the end, do not forget to post your "THANKS" to me for my teaching.