2 câu trả lời
$\Longrightarrow$
12×13-12×11
=12×(13-11)
=12×2
=24
17×27-27×19
=27×(17-19)
=27×(-2)
=-54
19×15-19×11
=19×(15-11)
=19×4
=76
`12xx13-12xx11=12xx(13-11)=12xx2=24`
`17xx27-27xx19=27xx(17-19)=27xx(-2)=-54`
`19xx15-19xx11=19xx(15-11)=19xx4=76`