Question 1011739
An animal shelter spends $4.50 per day to care for each bird and $5.00 per day to care for each cat. Sansa noticed that the shelter spent $146.00 caring for birds and cats on Wednesday. Sansa found a record showing that there were a total of 31 birds and cats on Wednesday. How many birds were at the shelter on Wednesday? 
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4.5b + 5c = 146 dollars
b + c = 31 
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Modify for elimination:
45b + 50c = 1460
50b + 50c = 50*31
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Subtract and solve for "b"::
5b = 90
b = 18 (# of birds)
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Cheers,
Stan H.
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