Question 625248: I'm 4o years old. My daughter is 9. How old will I be when I'm 3 times older than she is. I'm working on a formula that looks like this: 3x=x+31. 31 being how old I was at her birth. I'm interested in seeing how this formula is written, as well as how to solve it. Thanks.
Found 2 solutions by Alan3354, jim_thompson5910:
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! I'm 4o years old. My daughter is 9. How old will I be when I'm 3 times older than she is. I'm working on a formula that looks like this: 3x=x+31. 31 being how old I was at her birth. I'm interested in seeing how this formula is written, as well as how to solve it.
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The difference will always be 31 (30 or 32 sometimes, depending on bdays)
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3 times older = 4 times as old.
There's no integer solution for 4 times and 31.
m = mother's age
d = daughter's age
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m = d + 31
m = 4d
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4d = d + 31
3d = 31
d = 10 1/3 yrs
m = 41 1/3 yrs
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Same for 3 times, no integer solution.
31 is a prime number, so it doesn't work out.
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If the difference is, eg, 32 yrs, you can have several multiples with integers.
Answer by jim_thompson5910(35256)  (Show Source):
You can put this solution on YOUR website! Let x = number of years that pass from now
So in x = 1 year, you will be 40+x = 40+1 = 41 years old and she will be 9+x = 9+1 = 10 years old
So in general, after x years pass, you will be 40+x years old and she will be 9+x years old.
You want to know how long it will take for you to be 3 times as old as her in x years.
So this means that
(Your age in x years) = 3*(Her age in x years)
40+x = 3*(9+x)
So the equation is 40+x = 3*(9+x)
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Now let's solve 40+x = 3*(9+x)
40+x = 3*(9+x)
40+x = 27+3x
x = 27+3x-40
x-3x = 27-40
-2x = -13
x = -13/(-2)
x = 13/2
x = 6.5
Since this result is not a whole number, this means that you'll never be 3 times as old as her.
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