Answer: the weight of Jon's pet is
(3v - 25) pounds
Explanation:
The weight of Jon's dog is v pounds.
His cat weighs 21 pounds less than his dog. It means that the weight of his cat would be
(v - 21) pounds
His bunny weighs 3 pounds less than his cat. It means that the weight of his bunny would be
(v - 21) - 3 = (v - 24) pounds
Therefore, the weight of Jon's pets would be the sum of the weight of his dog, his cat and his bunny. It becomes
v + v - 21 + v - 24 = (3v - 25) pounds.