we have in total of coins are
5+6+10=21
For the first coin, we have the probability of 6/21
Then we only left 5 quarters and 20 coins in total, the next probability will be 5/20
the total probability is
[tex]\frac{6}{21}\cdot\frac{5}{20}=\frac{30}{420}=\frac{1}{14}[/tex]the answer is 1/14