Answer:
1/14
Step-by-step explanation:
The total number of coins in the bag is 10+6+5, or 21.
You reach into the bag and take ONE coin. The chances of that being a nickel is 6/21, or 2/7, since nickels compose 6 of the 21 coins in the bag.
You don't replace the nickel.
Now you have 20 coins in the bag, including 5 nickels.
The chances of your next draw being a dime is 5/20, or 1/4, since there are 5 dimes in the bag.
The joint probability of drawing a nickel and then a dime is then the product of these two probabilities:
(2/7)(1/4) = 2/28 = 1/14
