If there is a 28-foot garden with 4 equal sections, there are 7 feet to each section. If you only painted half of one section (7/2=3.5) you have only completed 3.5/28 of the job. To simplify, add 10 to both the numerator and the denominator to get 35/280, divide both top and bottom by 7, and 5/40 is simplified to 1/8. That is your answer; hoped this helped.