Question 1210402
.
There are 30 legs in my backyard but I'm counting dogs and kids.
How many kids and dogs are in my backyard?
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<pre>
x dogs and y kids.


Counting the legs, we can write an equation 

    4x + 2y = 30.


Thus we have one equation in non-negative integer numbers in two unknowns.


        +------------------------------------+
        |   It has more than one solution.   |
        +------------------------------------+


The possible solutions are listed in the Table below (every dog contributes 4 legs,
every kid contributes 2 legs)


    x dogs   y kids     total legs

       7        1     7*4 + 1*2  = 30  

       6        3     6*4 + 3*2  = 30      

       5        5     5*4 + 5*2  = 30    

       4        7     4*4 + 7*2  = 30    

       3        9     3*4 + 9*2  = 30    

       2       11     2*4 + 11*2 = 30    

       1       13     1*4 + 13*2 = 30    
</pre>

Solved.


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How this problem is posed in your post, it reminds me a horse with 3 legs,
because it is posed in an absurdist way.


To be posed correctly, in addition to the number of legs, the problem should provide the total number of "heads", 
i.e. the total number of the observed living beings in your backyards, which is missed in your post.


For similar problems, posed in a right way and solved properly, see the lessons


&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/misc/Problem-on-animals-at-a-farm.lesson>Problem on animals at a farm</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/misc/Problem-on-tablets-in-containers.lesson>Problem on pills in containers</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/misc/What-type-of-problems-are-these.lesson>What type of problems are these?</A> 


in this site.


From reading these lessons, learn how to pose and how to write your problems correctly.



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Problems like these are classics of the genre. They've been around for hundreds of years, and many generations have learned from them.


Therefore, they should be treated with the utmost respect. This means writing them with extreme care - not like you're doing in your post.