SOLUTION: The food you buy for your 15-horse herd lasts for 10 days. If you get 5 more horses, how long will that same amount of food last? (assume each horse eat about the same amount, I k

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Question 812706: The food you buy for your 15-horse herd lasts for 10 days. If you get 5 more horses, how long will that same amount of food last? (assume each horse eat about the same amount, I know this isn't true, but it's a good approximation given we don’t have any other information about the herd)
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = the 10 day supply of food for 15 horses
+x%2F15+ = the amount of food per horse for 10 days
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+15+%2B+5+=+20+ horses now
Now the same amount of food means
+x%2F20+ is the amount of food per horse
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Let +d+ = number of days the same
amount of food lasts
Now I can set up the ratio:
+%28+x%2F15+%29+%2F+%28+x%2F20+%29+=+10%2Fd+
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+20%2F15+=+10%2Fd+
+20d+=+150+
+d+=+7.5+
The same amount of food lasts 7.5 days