Answer:
Number of small dogs signed up to compete is 42.5. This is not possible as 0.5 dogs doesn't make sense. The data given could be wrong, in that case you can follow the same procedure and replace the data.
Explanation:
We can do this by building an equation.
Lets take the number of small dogs is

Then,
The number of Large dogs will be

The total number of dogs signed up is given as 49.
Therefore,
Number of Small Dogs + Number of Large Dogs = 49
⇒

=

=

=

=

Therefore, number of small dogs signed up to compete is 42.5. This is not possible as 0.5 dogs doesn't make sense. The data given could be wrong, in that case you can follow the same procedure and replace the data.