algebra 1 help >.<
I just need an equation.
We have these annoying little problems of the week, and this one stumped me.
"This year, Mrs. Nelson is three times as old as her sister. However, six years ago, she was five times as old as her sister."
The answer is 36, but I need help on how to explain this on half a page of college-ruled paper...
Is there a specific equation I could put to start, then expand on that?
i am braindead today, so maybe thats why...
thanks in advance.
September 16, 2010
12 Comments • Newest first
[quote=theNorm]The simple math being used is intuitively the most basic form of linear algebraic problem solving.[/quote]
It's still simple math.
Let's say Nelson's age = x and her sister's age = y
Since she is 3x her age,
x = 3y
6 years ago she was 5x her age, therefore
x - 6 = 5(y - 6)
now substitute the first equation into the second one, since you know that x = 3y:
x - 6 = 5(y - 6)
3y - 6= 5y - 30
2y = 24
y = 12
y = 12 means her sister is 12 years old.
12 x 3 = 36 so Nelson is 36 years old.
[quote=waterftw]n=3x
n-6=5x
and then i dunno the rest[/quote]
You forgot to decrease the sister's age (x) by 6.
[quote=theNorm]This is a system of equations. You learn all about them in linear algebra.[/quote]
But by using simple math, you get:
3x-6=5x-30
Tada.
[quote=Vuxrian]sorry it hurts my head[/quote]
hurts mine, too...
any helpers/ :[
sorry it hurts my head
Oh crap, stupid of me.
This year, Mrs. Nelson is three times as old as her sister. However, six years ago, she was five times as old as her sister. How old is she now?
answer = 36
sorry, hope I cleared it up
[quote=FieryStaff]I am attempting to explain the answer of 36, but I don't have something to base it off of.
I preferably want an equation, but the ones I make up just confuse me.
A simple equation I can do step-by-step on the explanation sheet, and then explain the rest verbally, on half a page of college ruled paper.[/quote]
See my equations. It's actually 2 equations because there's 2 scenarios, and it's impossible to solve if they just gave you 1 thing.
[quote=Omelet]What's the question?
Like, what are you trying to find?[/quote]
I am attempting to explain the answer of 36, but I don't have something to base it off of.
I preferably want an equation, but the ones I make up just confuse me.
A simple equation I can do step-by-step on the explanation sheet, and then explain the rest verbally, on half a page of college ruled paper.
What's the question?
Like, what are you trying to find?
y=3x
y-6=5(x-6)
y=Mrs. Nelson
x=sister
[quote=Heatless]I would just guess and check, but then again I'm not that smart.[/quote]
I did, and I got 36 as the answer.
I need help explaining the answer.