Question 1173582
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    Robert + Kevin + Monica    = 37


      x    + (x-9) + ((x-9)+4) = 37


      x    +  x-9  +   x-5     = 37


          3x   -  14           = 37


          3x                   = 37 + 14 = 51


           x                             = 51/3 = 17.


<U>ANSWER</U>.  Robert is 17 years old;  Kevin is  17-9 = 8 years old;  Monica is 8+4 = 12 years old.
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Solved.