
Step-by-step explanation
Probability is simply how likely something is to happen. Probability of event to happen P(E) = Number of favourable outcomes/Total Number of outcomes.

so
Step 1
Let
Number of studenst tha have a dog, given the do ot have a cat
=9
so

and
total students = 3+9+2+13=27
so

finally, replace

therefore, the answer is

I hope this helps you