a)
[tex]0.8 \times 100 = \frac{8}{10} \times 100 = 80[/tex]
b)
<AOC=<AOB+<BOC=100+80=180 => AOC - unghi alungit=> A,O,C coliniare
c)
[tex] \frac{2}{5} \times 100 + \frac{1}{4} \times 80 = 2 \times 20 + 20 = 40 + 20 = 60[/tex]
