Question 625444
Call the goats go and the geese ge.  Each goat and each goose has 1 head, so the total number of heads is go + ge = 35.  Express number of goats as go = 35-ge.
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Each goat has 4 legs, each goose has 2 legs, so the total number of legs is 4 go + 2ge = 100.  Substitute go in terms of ge (from above).<P>
4(35-ge) +2ge = 100  Solve for ge<P>
140-4ge + 2ge = 100 so 40=2ge and ge=20.  There are 20 geese, and thus 35-20=15 goats.
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