SOLUTION: Ten years ago Linda was three times christys age then. Ten years from now christys age will be 4/7 of Linda’s age then. How old are they now.

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Question 1202331: Ten years ago Linda was three times christys age then. Ten years from now christys age will be 4/7 of Linda’s age then. How old are they now.
Found 4 solutions by mananth, ikleyn, Edwin McCravy, MathTherapy:
Answer by mananth(16946)   (Show Source): You can put this solution on YOUR website!
Ten years ago Linda was three times christys age then. Ten years from now christys age will be 4/7 of Linda’s age then. How old are they now.
let christy's age 10 years ago be x
Linda's age was 3x
Ten years hence
Christy will be x+20 years
Linda'sage will be 3x +20
x+20 = 4/7 *3x
7(x+20) = 12x
7x+140 = 12x
5x = 140
x = 28 ( christy's age 10 years ago)
So Christy is 28 + 10 = 38 years
Plug x=28
Linda is 3x+10 = 84+20 =94 years



Answer by ikleyn(52799)   (Show Source): You can put this solution on YOUR website!
.
Ten years ago Linda was three times Christy's age then. Ten years from now
Christy's age will be 4/7 of Linda’s age then. How old are they now.
~~~~~~~~~~~~~~~~~~~~


            I read, interpret and solve the problem in different way;
            so my numbers are different from that of @mananth.


Let x years be the Christy's age 10 years ago;
then Linda's age at that time was 3x years.


Ten years from now Christy's age will be  (x+20) years;
                   Linda's   age will be (3x+20) years then.


So, I write equation as the problem states

    x + 20 = .


Simplify and find x

    7x + 140 = 12x + 80

    140 - 80 = 12x - 7x

       60    =    5x

        x    =    60/5 = 12.


ANSWER.  Christy's age now is 12+10 = 22 years.  Linda's age now is 3*12+10 = 46 years.


CHECK.   You may check it on your own that the condition of the problem 
         "in ten years" is satisfied.

Solved.



Answer by Edwin McCravy(20059)   (Show Source): You can put this solution on YOUR website!
I would set it up this way.  This translates it literally just as it's stated.



The answer comes out same as Ikleyn's. L = 46, C = 22

Edwin

Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!
Ten years ago Linda was three times christys age then. Ten years from now christys age will be 4/7 of Linda’s age then. How old are they now.

This is as clear as "daylight," so I don't know how 1 of these people didn't get it. It's not 
surprising though, considering the vast number of wrong answers he/she has been known to produce.

Let Christy's and Linda's ages, be C and L, respectively
Then 10 years ago, Christy was C - 10, while Linda was L - 10
We then get their AGE equation, 10 years ago as L - 10 = 3(C - 10)____L - 10 = 3C - 30___L = 3C - 20 ----- eq (i)

In 10 years' time, Christy will be C + 10, while Linda will be L + 10
We then get their AGE equation, 10 years from now, as 
                                                     7C + 70 = 4(L + 10) ------ Multiplying by LCD, 7
                                                     7C + 70 = 4L + 40
                                                     7C - 4L = - 30 ------ eq (ii)
                                             7C - 4(3C - 20) = - 30 ----- Substituting 3C - 20 for L in eq (ii)
                                               7C - 12C + 80 = - 30
                                                        - 5C = - 110'
                                        Christy's age, or 

Knowing Christy's age, you can now find Linda's age using eq (i)!

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