SOLUTION: My problem : At a recent birthday party for a friend of mine, I pointed out the following to my friend: Thirteen years ago, you were half as old as you will be five years from no

Question 134417: My problem : At a recent birthday party for a friend of mine, I pointed out the following to my friend: Thirteen years ago, you were half as old as you will be five years from now. What was my friend's age?

I have no work to show on this one because the sample(below) shows that Im doing formula all wrong....Please help me see where I am going wrong. Its been a while and Im obviously close but too rusty :P
SAMPLE: At a recent birthday party for a friend of mine, I pointed out the following to my friend: Eighty-eight years ago, you were one-third as old as you will be six years from now.
My answer: 123 correct answer was 135
Sample problem solutions 88+6=94/3=31+94=125 or 88/3=29+88+6=123
Thank you really for taking the time having done tutoring myself I appreciate what you guys are doing here.
Found 2 solutions by vleith, jim_thompson5910:
Answer by vleith(2983) (Show Source): You can put this solution on YOUR website!
Let x be your friend's age.
Given :

Check your answer. Is 31 - 13 equal to (31+5)/2 ???
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Let f=age of friend

The phrase "13 years ago" can be written as and the phrase "five years from now" can be written as

Now since "Thirteen years ago, you were half as old as you will be five years from now", this means that we simply take half of to get

Now set the two expressions and equal to each other

Multiply both sides by 2.

Multiply

Add 26 to both sides

Subtract f from both sides

Combine like terms on the left side

Combine like terms on the right side

--------------------------------------------------------------
Answer:
So our answer is

This means that the friend is 31 years old

Notice how if we subtract 13 from 31 we get . So 13 years ago s/he was 18

Now add 5 to 31 to get

And we can see that 18 is half of 36

So we can see that our answer is correct.

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