Question 1202331
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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 {{{matrix(1,3, C + 10, "=", (4/7)(L + 10))}}}
                                                     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 {{{highlight_green(matrix(1,5, C, "=", (- 110)/(- 5), "=", highlight(22)))}}}

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