Brianna is constructing a raised flower bed in the shape of a rectangle. the length of the flower bed is equal to the width plus 3 feet. the perimeter of the flower bed is 14 feet. she is using railroad ties as the border. she has enough railroad ties for all but one length of the flower bed. how long of a railroad tie does brianna need to purchase? how long of a railroad tie does brianna need to purchase? use the five-step problem-solving plan