So the puppy weighs 23 pounds in the beginning. Since he gain three pounds every months, and we are asking for five months, we can use 5×3 since five months and gains three pounds. Then you get 15 pounds, you can answer it as he gained 15 pounds. If you want to continue it, then yku can do 15+23 which you will get 38 as your answer for his weight after five months.