First part:
65 cats divided by the ratio of 5 = 13.
13 x ratio of 7 dogs = 91 dogs are at the show.
Second part:
65 cats + 91 dogs = 156 pets are at the show.
Third part: I think the ratio is 7:12. I found the lowest common multiple, which is 13.
91 dogs divided by 13 is 7.
156 pets overall divided by 13 is 12.
Thus, the answer of 7:12.
Hope this helps! Make sure you show your work, for example the addition, multiplication, and division parts of it. :) It shouldn't be too hard, unless you want me to do that as well.