# Thread: Algebra problem->Check if right,pls

1. ## Algebra problem->Check if right,pls

I'm having a hard time learning how to translate a written math problem into algebra equations. Tell me if this is right?

The difference of two number, x and y, is 28. The number y is 8/9 of the number x. Find these 2 numbers.

$\displaystyle x-y = 28$
$\displaystyle 8/9 x = y$

$\displaystyle -8(x-y) = -8(28)$
$\displaystyle -8x-8y=-224$

$\displaystyle 8/9x=y$
$\displaystyle 9(8/9x)=9(y)$
$\displaystyle 8x=9y$
$\displaystyle 8x-9y=0$

$\displaystyle -8x-8y=-224$
$\displaystyle +8x-9y=0$
$\displaystyle -17y=-224$
$\displaystyle y=224/17$

$\displaystyle x-y=28$
$\displaystyle x-224/17=28$
$\displaystyle x=28+224/17$
$\displaystyle x= 700/17$

$\displaystyle x-y=28$
$\displaystyle 700/17-224/17=28$
$\displaystyle 28=28$

So what do you guys think?

2. This part is wrong.

Originally Posted by Neenoon

$\displaystyle -8(x-y) = -8(28)$
$\displaystyle -8x-8y=-224$
it should be $\displaystyle -8x + 8y=-224$

You got the 2 equations right you solve the system wrong. The way you solve the problem is a bit complicated.
Here is how I would do it.

$\displaystyle x-y=28$
$\displaystyle y= \frac {8} {9} x$

so

$\displaystyle x-\frac {8} {9} x=28$
$\displaystyle \frac {1} {9} x=28$
$\displaystyle x= 252$

Plug x into the equation
$\displaystyle 252-y=28$
$\displaystyle y=224$

3. Duh

Let's say I was tired when I did these!

Thanks a whole bunch, 5 points that would have been gone right there!

4. Originally Posted by Neenoon
I'm having a hard time learning how to translate a written math problem into algebra equations. Tell me if this is right?

The difference of two number, x and y, is 28. The number y is 8/9 of the number x. Find these 2 numbers.

$\displaystyle x-y = 28$
$\displaystyle 8/9 x = y$

$\displaystyle -8(x-y) = -8(28)$
$\displaystyle -8x-8y=-224$

$\displaystyle 8/9x=y$
$\displaystyle 9(8/9x)=9(y)$
$\displaystyle 8x=9y$
$\displaystyle 8x-9y=0$

$\displaystyle -8x-8y=-224$
$\displaystyle +8x-9y=0$
$\displaystyle -17y=-224$
$\displaystyle y=224/17$

$\displaystyle x-y=28$
$\displaystyle x-224/17=28$
$\displaystyle x=28+224/17$
$\displaystyle x= 700/17$

$\displaystyle x-y=28$
$\displaystyle 700/17-224/17=28$
$\displaystyle 28=28$

So what do you guys think?
Hi!
u can get this answer through solve the equation method also