Question 1147240
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Let Mary's age will be x years.


Then the grandmother's age is  (9x - 11) years.


According to the condition,


    x + (9x-11) = 69.


Simplify and solve for x


    10x = 69 + 11

    10x = 80

      x = 80/10 = 8.


<U>ANSWER</U>.  Mary is 8 years old;  her grandmother is  69-8 = 61 years old.


<U>CHECK</U>.   8*9 - 11 = 72 - 11 = 61 years.  ! Correct !
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Solved.