74,4x2/21+(-105,3)x2/3/7 -(-105,3)2/21x74,7=

1. 74,4*2:21 = 7,0862. -105,3*2:3:7 = -10,033. -105,3*2:21*74,7 = 749,1344. 7,086 + (-10,03) - (749,134) = 746,19