Question 1012773
Call the number of birds and cats, b and c.  Then we can write
1.50b + 7c = 74.50  and
b + c = 24
Let's multiply the second one by 7 and subtract from the first one...
1.50b + 7c = 74.50
-(7b + 7c = 168)
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-5.5b = -93.50
and
b = 17 birds
c = 24 - 17 = 7 cats