Question

An animal shelter spends $5.50 per day to care for each bird and $8.50 per day to care for each cat. Anna noticed that the shelter spent $291.50 caring for birds and cats on Thursday. Anna found a record showing that there were a total of 41 birds and cats on Thursday. How many birds were at the shelter on Thursday?

Answer 1

Answer:

19

Step-by-step explanation:

We can solve this problem using a system of equation in two unknowns.

Let b = number of birds.

Let c = number of cats.

The care of a bird costs $5.50, so for b number of birds, the cost of care is 5.5b.

The care of a cat costs $8.50, so for c number of cats, the cost of care is 8.5c.

The total cost of care for the birds and cats is 5.5b + 8.5c.

The total cost of care is $291.50. This must equal the expression we have above, so we get our first equation.

5.5b + 8.5c = 291.5

The total number of birds and cats is b + c, but we are told it is 41, so our second equation is:

b + c = 41

We now have the following system of two equations in two unknowns.

5.5b + 8.5c = 291.5

b + c = 41

Rewrite the first equation.

Multiply both sides of the second equation by -8.5, and write it under the first equation. Then add the equations.

      5.5b + 8.5c = 291.5

+    -8.5b - 8.5c = -348.50

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        -3b            = -57

Divide both sides of the equation by -3.

b = 19

Answer: there were 19 birds