We have that Alex filled
[tex]\frac{2}{7}\text{ and }\frac{4}{7}[/tex]of his binder.
We just add both fractions.
Then, in total he filled:
[tex]\frac{2}{7}+\frac{4}{7}[/tex]Since both fractions have the same denominator, 7, we add them just by adding the numerators:
[tex]\frac{2}{7}+\frac{4}{7}=\frac{2+4}{7}=\frac{6}{7}[/tex]Then, he filled 6/7 of his binder in those two days.
Answer: 6/7