SOLUTION: My question is how to substitute x+y to 4x+2y. the problem is: There are 25 heads and 100 legs,x chicken(2 legs) and y pigs(4 legs). The answer is 25 pigs but I need equations to

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Question 335897: My question is how to substitute x+y to 4x+2y. the problem is: There are 25 heads and 100 legs,x chicken(2 legs) and y pigs(4 legs). The answer is 25 pigs but I need equations to get to 1x=25 here is what I have so far

Answer by Edwin McCravy(20056)   (Show Source): You can put this solution on YOUR website!

It is obvious that they all have to be pigs with no chickens,
since 100=4*25, there are 4 times as many legs as there are heads,
and of course there are 25 pigs and no chickens.  So this is a strange
problem.  I hope the problem didn't state that there had to be some 
chickens, since there aren't any.  But anyway, we'll go through what 
was giving you trouble.



Solve the first equation for either letter.  I will
arbitrarily choose to solve the first equation for y




Next substitute  for y in the second equation:







So since





So there are 25 pigs and no chickens.

Edwin
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