Fabio and gwen are saving money to buy a new gaming station. they need at least $510 to purchase the new gaming station. gwen weeds yards and fabio walks dogs to raise money. gwen charges $12 each time she weeds a yard and fabio charges $9 each time he walks a dog. the number of dog walks that fabio has scheduled is no more than twice the number of yards gwen has scheduled to weed. fabio will walk at least 25 dogs. write a set of constraints to model the problem, with x representing the number of lawns weeded and y representing the number of dogs walked.