The first week of January, there are 49 dogs and 28 cats in an animal shelter. Throughout the month the ratio of dogs to cats remains the same. The last week of January there are 20 cats in the animal shelter. How many dogs are there?

35 dogs

Step-by-step explanation:

We can simplify the ratio 49:28 by dividing by 7

The new ratio is 7:4 which is easier to work with.

It says there are 20 cats so we know that for every 4 cats there are 7 dogs

We simply multiply 20 by 7/4

20 x 7/4 = 35 so  there are 35 dogs

you didn't post any answer choices, so its not 100% clear what your teacher is looking for

however, log(15/7) is equivalent to log(15) - log(7)

i'm using the rule log(x/y) = log(x) - log(y)