SOLUTION: My car will be twice as old in four years as it was three years ago. How old is my car?

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Question 1148957: My car will be twice as old in four years as it was three years ago. How old is my car?
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52786)   (Show Source): You can put this solution on YOUR website!
.

x + 4 = 2*(x-3).


Solve and get the answer.


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Should I explain that this Algebra solution is much simpler than the logic analysis by @greenestamps,
or it is clear to you without my explanations ?


/\/\/\/\/\/\/\/

This my note is specially for @greenestamps, in connection with his post. 

    A "golden rule" of teaching (one of some basic rules of teaching) says:


        "A good teacher should say truth and only truth to students, but not all the truth."

I read this wisdom somewhere several years ago, but just not able to remember the source and to refer on it . . .



Answer by greenestamps(13200)   (Show Source): You can put this solution on YOUR website!


Using logical reasoning instead of formal algebra....

The difference between "in four years" and "three years ago" is 7 years.

If that difference is 7 years, and the age of the car in 4 years is 2 times its age 3 years ago, then the car's ages 4 years from now and 3 years ago have to be 14 and 7.

So the current age of the car is 14-4=10 years (or 7+3=10 years).
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