Ava and Julia are saving money to go to an amusement park. After looking at all the costs, they determine they need at least $250 to go on the trip. Ava walks dogs and Julia waters flowers to raise the money. Ava charges $3.50 each time she walks a dog. Julia charges $1 each time she waters the flowers. The number of times Julia plans to water the flowers is no more than five times the number of dogs Ava plans to walk. Ava plans to walk no less than 14 dogs.

Write a set of constraints to model the problem, with d representing the number of dogs walked and f representing the number of times flowers were watered. You should write a total of 3 constraints.