57/37*74/85; 81/115*46/81; 3/16*4; 23*5/46

57/37 * 74/85 = (57 * 74) / (37 * 85) = (74 и 37 сокращаем на 37) = (57 * 2) / 85 = = 114/85 = 1 29/85 81/115 * 46/81 = (81*46) / (115*81) = 46/115 сокращаем на23 = 2/5 3/16 * 4 = (3*4) / 16 сокращ. на 4 = 3/4 23*5/46 = 5/2 = 2.5