Question

The function y = -3x + 42 models the average number of dogs at an animal shelter, where x is the number of days after July 1. The function y = 4x + 7 models the average number of cats at the animal shelter, where x is the number of days after July 1. After how many days is the average number of cats and dogs at the shelter the same?

A. 5 days
B. 7 days
C. 35 days
D. 49 days

Answer 1

A. 5 days

Explanation:

Average number of dogs at an animal shelter: y = -3x + 42

Average number of cats at the animal shelter: y = 4x + 7

Where,

x = number of days after July 1

After how many days is the average number of cats and dogs at the shelter the same?

Equate both functions

-3x + 42 = 4x + 7

-3x - 4x = 7 - 42

-7x = -35

Divide both sides by -7

x = -35 / -7

= 5

x = 5 days

The correct answer is A. 5 days