SOLUTION: Please help me solve this equation:Daniel is three times as old as kathryn. seven years ago, daniel was five times as old as kathryn. How are old they?

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Question 1038595: Please help me solve this equation:Daniel is three times as old as kathryn. seven years ago, daniel was five times as old as kathryn. How are old they?
Found 2 solutions by josmiceli, ikleyn:
Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!
Let = Daniel's age now
Let = Kathryn's age now
-------------------------------
(1)
(2)
---------------------------
This is 2 equations and 2 unknowns,
so it's solvable
Substitute (1) into (2)
(2)
(2)
(2)
(2)
(2)
and
(1)
(1)
---------------------
Daniel is 42
Kathryn is 14
---------------------
check:
(2)
(2)
(2)
(2)
OK
Answer by ikleyn(52788)   (Show Source): You can put this solution on YOUR website!
. Please help me solve this equation:Daniel is three times as old as kathryn. seven years ago, daniel was five times as old as kathryn. How are old they?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

D = 3K            (1)     (Daniel is three times as old as kathryn)
D-7 = 5*(K-7)     (2)     (Seven years ago . . . )

Substitute the expression (1) for D into (3).

Then solve the single equation for K.

It is how all (almost all) age problems are solved.

See the lessons
    - Age problems and their solutions
    - A fresh formulation of a traditional age problem
    - Really intricate age word problem
    - Selected age word problems from the archive
    - Age problem for the day of April, 1
in this site.


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