Mrs. Farnsworth's dog was 12 pounds when she adopted her. If her dog gained 3 pounds a week for the first 6 months how many weeks would it take for her to be 45 pounds?

Answer 1

Her dog gains 12*3=<<12*3=36>>36 pounds a month
So after 6 months, her dog would weigh 12+36*6=<<12+36*6=228>>228 pounds
To get her dog to be 45 pounds, it would take 45-12=<<45-12=33>>33 additional pounds.
Thus, it would take 33/3=<<33/3=11>>11 weeks. Answer: \boxed{11}.