119. Tính bằng 2 cách
a) C1: 15.12-3.5.10 = 180-150 = 30
C2: 15.12-3.5.10 = 15.12-15.10 = 15.(12-10) = 15.2 = 30
b)C1: 45-9.(13+5) = 45-9.18 = 45- 162 = -117
C2: 45-9.(13+5) = 45-9.13-9.5 = 45-117-45 = -117
c)C1: 29.(19-13)-19.(29-13) = 29.6-19.16 = 174-304 = -130 C2:29.(19-13)-19.(29-13) =29.19-29.13-19.29+19.13 =(29.19-19.29)+(19.13-29.13) = 0+13.(19-29) =13.(-10) = -130