a) 25,3:5-0,36:6+2,1-28 = 5,06 - 0,06 + 2,1 - 28 = 5 + 2,1 - 28 = 7,1 - 28 = -20,9
б) 37,925-1000-37,925:10 = 37,925 - 1000 - 3,7925 = -962,075 - 3,7925 = -965,8675