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The sum of the present ages of Kathy and Samantha is 60 years. In 8 years, Kathy will be 5 years older than 3 times as old as Samantha was 3 years ago. How old are they now? Write it in a equation

User Mike Kale
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1 Answer

2 votes

Answer:

Kathy is 48 years old and Samantha is 12.

Explanation:

This is a challenging question that requires some interpretation. Let K and S stand for the current ages of Kathy and Samatha.

We are told that: K+S = 60

And, in 8 years: K+8 and S+8

"Kathy will be 5 years older than 3 times as old as Samantha was 3 years ago" ["3 years ago:" from now or in 8 years. I'll interpret it as from now, or (S-3)]

(K+8) = 3(S+8-3)+5 ["5 years older than 3 times as old as Samantha was 3 years ago"]

(K+8) = 3(S+5)+5

K+8 = 3S+20

K = 3S+12

---

Rearrange the firts equation to isolate K

K = 60-S

Now use this definition of K in the previous equation:

K = 3S+12

60-S = 3S+12

4S = 48

S = 12

K+S = 60

K+12 = 60

K = 48

=====

CHECK

Does K + S = 60? 48+12 = 60 YES

In 8 years, will Kathy will be 5 years older than 3 times as old as Samantha was 3 years ago?

K = 48+8 = 56

S = 12+8 = 20

Three years ago S was 9.

(K+8) = 3(S+8-3)+5

(K+8) = 3(12+8-3)+5

K + 8 = 3(17)+5

K = 48

===

Kathy is 48 years old and Samantha is 12.

User Rupert Pupkin
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