SOLUTION: John is 10 years younger than two times Mary. Mary’s age is to her mother’s age as John’s age is to his father’s age. Mary’s mom is 36 and John’s father is 40. How old is John?

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Question 1109642: John is 10 years younger than two times Mary. Mary’s age is to her mother’s age as John’s age is to his father’s age. Mary’s mom is 36 and John’s father is 40. How old is John?
Found 3 solutions by stanbon, TeachMath, greenestamps:
Answer by stanbon(75887) About Me  (Show Source):
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John is 10 years younger than two times Mary. Mary’s age is to her mother’s age as John’s age is to his father’s age. Mary’s mom is 36 and John’s father is 40. How old is John?
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J = 2M-10
M/m = J/f
m = 36 ; f = 40
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J = 2M-10
M/36 = J/40
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J = 2M-10
J = (40/36)M
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2M-10 = (10/9)M
(1 1/9)M = 10
(10/9)M = 10
Mary = 9 years
J = 2M-10 = 8 years
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Cheers,
Stan H.
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Answer by TeachMath(96) About Me  (Show Source):
You can put this solution on YOUR website!
Doesn't make any sense. No INTEGER value for John's age.

Answer by greenestamps(13203) About Me  (Show Source):
You can put this solution on YOUR website!


Tutor stanbon has an error in his calculations; his answer is not correct.

Tutor teachmath is right -- the given information does not produce whole number values for John's age.

If Mary's age is m, then John's age is 2m-10. The given information says

%282m-10%29%2F40+=+m%2F36
72m-360+=+40m
32m+=+360
m+=+360%2F32+=+45%2F4

That has to be a whole number. Since it is not, the problem is flawed.