Since there are 6 equal parts and Theo planted in only 5 of them, he planted seeds in 5/6 of the garden (OR 5/6 = 10/12 = 15/18 = 20/24 = 25/30 = 30/36 = 35/42 = 40/48 = 45/54 = 50/60 = 55/66 = 60/72 = 65/78 = 70/84 = 75/90 = 80/96 = 85/102 = 90/108 = 95/114 = 100/120 - from https://goo.gl/RTbV4R)
I hope this helps. This may not be 100% correct, but it is what i believe to be the answer. :)
