a) 108/960 = (108 ÷ 12)/(960 ÷ 12) = 9/80
б) 256/640 = (256 ÷ 64)/(640 ÷ 64) = 4/10 = 2/5
в) 360/840 = (360 ÷ 120)/(840 ÷ 120) = 3/7
г) 333/1290 = (333 ÷ 3)/(1290 ÷ 3) = 111/430