Question

Karl’s and eddie’s ages added together are equal to 65. 10 years ago, Karl was twice as old as Eddie. How old are they now

Answer 1

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Answer:

• Karl is 40
• Eddie is 25

Explanation:

10 years ago, the sum of their ages was 65 -2·10 = 45.

If Karl was twice as old as Eddie, his contribution was 2/3 of the sum and Eddie's was 1/3. That is, Karl was (2/3)(45) = 30 and Eddie was 15 at that time.

Now, Karl is 40 and Eddie is 25.

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This can be solved using a system of equations.

e = 65 -k

(k -10) = 2(e -10)

Substituting the first equation into the second gives ...

k -10 = 2((65 -k) -10)

k -10 = 110 -2k . . . . . . . simplify

3k = 120 . . . . . . . . . . . . add 10+2k

k = 40

e = 65 -40 = 25