2014 . 2018 - 2012 . 2020
= (2012 + 2).2018 - 2012.(2018 + 2)
= (2012.2018 + 2.2018) - (2012.2018 + 2012.2)
= 2012.2018 + 2.2018 - 2012.2018 - 2012.2
= 2.2018 - 2.2012
= 2.(2018 - 2012)
= 2.4
=8
@Thùy Linh
2014 . 2018 - 2012 . 2020
= 2014 . 2018 - (2012 . 2018 + 2012 . 2)
= (2014 . 2018 - 2012 . 2018) - 2012 . 2
= 2 . 2018 - 2012 . 2
= 6 . 2
= 12