Salut!
a) 2020+2021 x 2020 - 2022 + 2019=
2020(1+2021) - 2022 + 2019=
2020 x 2022 - 2022 + 2019=
2022(2020-1) +2019=
2022 x 2019 + 2019=
2019(2022+1)=
2019 x 2023=
=4084437
b) (5+10+15+...+100):(1+2+...+10)=
5(1+2+3+...+20):(1+2+3+...+10)=
[5(20x21/2)]:(10x11/2)=
5(10x21):(5x11)=
5x210:55=
1050:55=
=19,(09)
Succes!
