Question 821784
A zoo has lions and ostriches. Pet Sitting guy sees 15 heads and 50 legs. 
How many lions are there?
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Head Equation: L + O = 15
Legs Equation:4L +2O = 50
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Modify for eliminatiion:
4L + 4O = 4*15
4L + 2O = 50
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Subtract and solve for "O":
2O = 10
O = 5 (# of ostriches)
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Solve for "L"
L + O = 15
L + 5 = 15
L = 10 (# of lions)
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cheers,
Stan H.
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