Question 821787
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Hi,
A zoo has some lions and ostriches. 
A zoo has {{{green(x)}}} lions  and {{{green(y)}}}ostriches 
Pet Sitting guy spoke 15 heads and 50 legs. How many lions?
   x + y = 15  0r  y ={{{ 15-x}}}
  4x + 2y = 50
  4x + 2(15-x) = 50   |Substituting for y
         2x = 20
          x = {{{highlight_green(10)}}} lions
  CHECKING our answer***
  40 + 10 = 50 legs