Answer:
3 dogs and 5 cats were adopted out on Christmas eve.
Explanation:
Let the number of dogs adopted out on Christmas eve be x and the number of cats be y.
From the question,
On Christmas Eve, the animal adopted out 8 total animals
That is, x + y = 8 ...... (1)
and brought in $400 in total adoption fees.
Also from the question,
Each dog adoption fee was $75 and each cat adoption fee was $35.
∴ On Christmas Eve,
75x + 35y = 400 ...... (2)
Now, to determine how many dogs and how many cats were adopted out on Christmas Eve, we will solve the two equations simultaneously.
From equation (1)
x + y = 8
Make x the subject of the relation.
∴ x = 8 - y ...... (3)
Substitute the value of x into equation (2)
75(8 - y) + 35y = 400
600 - 75y + 35y = 400
600 -40y = 400
600 - 400 = 40y
200 = 40y
∴ 40y = 200
y = 200/40
y = 5
Substitute the value of y into equation (3)
x = 8 - y
x = 8 - 5
x = 3
∴ x = 3 and y = 5
Hence, 3 dogs and 5 cats were adopted out on Christmas eve.