SOLUTION: 7. At some point during the lives of you and the youngest person, your age will be three times his/her age at that moment. Write an equation which models how old in years each of y

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Question 880156: 7. At some point during the lives of you and the youngest person, your age will be three times his/her age at that moment. Write an equation which models how old in years each of you will be when you are three times as old as the younger person.
I was 25 when she was born. I can not figure out how to write the equation.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The difference in their ages never changes
I can call this difference +c+
Let +x+ = the age of the younger person
Let +y+ = the age of the older person
+y+=+x+%2B+c+
I want the age of the older person to be +3x+, so
+3x+=+x+%2B+c+
+c+=+2x+
+x+=+c%2F2+
------------
+y+=+c%2F2+%2B+c+
+y+=+%283%2F2%29%2Ac+
This is telling me that when the older person is 3/2
times the difference in their ages, then the older
person will be 3 times the age of the younger
----------------
To test this, I'll say
Older person = 42
Younger person = 9
+c=+42+-+9+
+c+=+33+
and
+%283%2F2%29%2A33+=+49.5+
Older = +49.5+
Younger = +49.5+-+33+
Younger = +16.5+
-------------------
check:
+49.5+=+3%2A16.5+
+49.5+=+49.5+
It works