397x18-18x254=(397-254)x18
=143x18
=2574
809x5-354x5=(809-354)x5
=455x5
=2275
397 x 18 - 18 x 254 809 x 5 - 354 x 5
= 18 x ( 397 - 254 ) = 5 x ( 809 - 354 )
= 18 x 143 = 5 x 455
= 2574 = 2275
a) C1 : 397 x 18 - 18 x 254 b) 809 x 5 - 354 x 5
= 18 x ( 397 - 254 ) = 5 x ( 809 - 354 )
= 18 x 143 = 5 x 455
= 1144 = 2275
a x 26 + a x 107 – a x 32 – a với a = 234.