48/72 = 8x6/8x9 = 6/9 = 3x2/3x3 = 2/3

56/77 = 7x8/7x11 = 8/11

648/720 = 2x324/2x360 = 324/360 = 162x2/180x2 = 162/180 = 81x2/90x2 = 81/90 = 9x9/9x10 = 9/10