18/27 = (18/9) / (27/9) = 2/3
27/36 = (27/9) / (36/9) = 3/4
72/63 = (72/9) / (63/9) = 8/7
45/72 = (45/9) / (72/9) = 5/8
18/27 = (18/9) / (27/9) = 2/3
27/36 = (27/9) / (36/9) = 3/4
72/63 = (72/9) / (63/9) = 8/7
45/72 = (45/9) / (72/9) = 5/8