Question 1111461
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Cindy       + Brother = 23


(Brother+7) + Brother = 23


2*Brother + 7 = 23


2*Brother = 23 - 7 = 16  ====>   Brother = {{{16/2}}} = 8.


<U>Answer</U>.  Brother is 8 years old.  Cindy is 8+7 = 15.


<U>Check</U>.  8 + 15 = 23   ! Correct !
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Solved.