Posted by Soroban on September 11, 2002 at 22:58:53:
In Reply to: My sons Algebra homework posted by Renee on September 11, 2002 at 22:45:07:
: Okay, He is working on word problems and this one has us stumped. Western State College is 18 years older than Southern State. Western State is also 2 1/2 times as old as Southern. How old is each? Choices for Southern State's ages are: 12, 14, 18.
: Anyone that could show me how to figure this out would be a savior! Thanks, Renee
It's all in the set-up, isn't it, Renee?
I don't if your son can handle two variables, but I'll use two.
If this doesn't work for him, let us know.
Let W = age of Western State, S = age of Southern State.
Try to translate the words into algebra.
"Western is 18 years older than Southern"
W = S + 18
"Western is 2 1/2 times as old as Southern"
W = (5/2)S
We have a "system of equations": 2 unknowns and 2 equations.
There are different methods for solving them. This is the fastest.
The equation says: W = (5/2)S, or 5S/2.
Use that to replace W in the first equation.
Then you have: 5S/2 = S + 18
And he should be able to finish it from here.