Question 1124068
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Petra + Mother        = 48


Petra + (2*Petra + 9) = 48


P + (2P +9) = 48


3P = 48 - 9


3P = 39  ====>  P = 39/3 = 13.


<U>Answer</U>.  Petra is 13 years old;  the mother is 2*13+9 = 35 years old.
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Solved.