We have in total 7 tiles
the probability of choosing a number less than 7 and then a multiple of 4 is
the number of tiles less than 7 are 2 tiles (6,5)
the number of tiles that are multiple of 4 are (8,20)
The probability
[tex]\frac{2}{7}\cdot\frac{2}{6}=\frac{2}{21}[/tex]