7th grade math
posted by Abby on .
Horses, pigs and cows is really easy I can do it in my head but, my teacher told me I would have to start showing my work. I really have no clue how to do that I have always done it in my head. Can you pretty please help me I would gladly appreciate it. Thank you. :)

I don't know what's in your head!!
What is the problem? 
Thanks Ms.Sue!!
My teacher gave me an example (I don't know so sorry)
28+38+34=100
h+p+c=50
h+(28h)+(34h)=50
h+62=50
62/50=50/50
12 = h
Thanks (it's really confusing) 
Please post a problem that you did in your head, and I'll try to help you.

(Blank) horses + (blank) pigs =22
(Blank) horses + (blank) cows =9
(Blank) pigs + (blank) cows =17
Hope that gives you an idea of what I am talking 'bout (if I could take a pic. I would)
Sorry I meant 22 
Are you working with variables?
let the number of horses be x
let the number of pigs be y
let the number of cows be z
so you have:
x+y = 22 #1
x+z = 9 #2
y+z = 17 #3
subtract #1  #2 > yz = 13 #4
add #3+#4 > 2y = 30
y = 15
sub into #1
x+y=22
x+15=22
x=7
sub into #2
x+z = 9
7+z = 9
z = 2
we have 7 horses, 15 pigs, and 2 cows 
Thanks Reiny :) (sorry its all ratchit and says lexie b/c my 'lil sis was putting a ? And 4got 2 put it back to Abby)