Question 837356: At some point during the lives of you and a person younger than you, your age will be (OR WAS) three times his/her age at that moment. Write an equation which models how old in years each of you will be (OR WERE) when you are (OR WERE) three times as old as the younger person
I am 43 and my daughter is 15
Answer by Edwin McCravy(20056)   (Show Source):
You can put this solution on YOUR website! At some point during the lives of you and a person younger than you, your age will be (OR WAS) three times his/her age at that moment. Write an equation which models how old in years each of you will be (OR WERE) when you are (OR WERE) three times as old as the younger person.Suppose your present age is A and the younger person's present age is B.
Let x = the number of years 'from now' or 'ago' (x is positive if in the
future, negative if in the past). Then your age at that time will be (or was)
A+x and the younger person's age at that time will be (or was) B+x.
A + x = 3(B + x)
We solve for x
A + x = 3B + 3x
A - 3B = 2x
  
The your age then will be (or was, if x is negative):
      .
The other person's age then will be (or was, if x is negative):
     .
Answer: If you are now A years old and the younger person is now B years old,
then when you are (or were) years old, the other person will
be (or was)  .
-------
I am 43 and my daughter is 15.
We substitute A=43 and B=15
and , and get:
 and 
Since you are now 43 years old and your daughter is 15 years old, then
when you were 42 years old, your daughter WAS 14.
[In this case x was negative (-1) and we had to go into the past, and
the time was 1 year ago].
Edwin
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