Question 1163475
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Mary x

Aldo (x-9)

Lamar 4*(x-9)


    x + (x-9) + 4*(x-9) = 99

    6x - 45             = 99

    6x                  = 99 + 45

    6x                  = 144

     x                  = 144/6 = 24.


From this point, complete the solution on your own.
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You obtained all needed instructions.