a)
[tex]80 \times (70 + 190) = 80 \times 70 + 80 \times 190[/tex]
b)
[tex]900 \times 700 \times 600 = 900 \times 600 \times 700 = 700 \times 900 \times 600[/tex]
c)
[tex]40 \times 901 + 60 \times 901 + 50 \times 901 = 150 \times 901[/tex]
