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Spiders and Flies
There was a big web with 13 spiders and flies on it. There were a total of 94 legs on the web. How many spiders are there?
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Jul 12, 2002
There was a big web with 13 spiders and flies on it. There were a total of 94 legs on the web. How many spiders are there?
... I am a bit confused. You have already specified that there were 13 spiders. Were you referring to any part of the web where there are 94 legs ??
... I am a bit confused. You have already specified that there were 13 spiders. Were you referring to any part of the web where there are 94 legs ??
Ravi, it quite clearly states there are 13 SPIDERS AND FLIES. Not just spiders, but a combination of both.
what he means is that spiders eat flies right, so there can only be spiders. so there are 8 spiders.
I know this is years old, but...shouldn't it be 84 legs??
My bad - I guess flies have 6 legs, not 4...
Let the number of spiders = s
Let the number of flies = f
s+f=13
f=13-s
8s+6f=94 (spiders have 8 legs, flies have 6 legs)
8s+6(13-s)=94 (by substitution)
8s+78-6s=94
2s+78=94
2s=94-78
2s=16
s=16/2
s=8 (spiders)
To verify:
f=13-s
f=13-8
f=5 (flies)
8s+6f=number of legs
8(+6(5)=
64+30=
94 (legs)
Let the number of flies = f
s+f=13
f=13-s
8s+6f=94 (spiders have 8 legs, flies have 6 legs)
8s+6(13-s)=94 (by substitution)
8s+78-6s=94
2s+78=94
2s=94-78
2s=16
s=16/2
s=8 (spiders)
To verify:
f=13-s
f=13-8
f=5 (flies)
8s+6f=number of legs
8(+6(5)=
64+30=
94 (legs)
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