Answer:
possibility is 1 in 6
Step-by-step explanation:
combinations of 2 coins are
5/10 , 5/20 , 5/50 → 3 possibles
10/20 , 10/50 → 2 possibles
20/50 → 1 possible
there are 6 possible combinations of the 2 coins
the only possible combination for 25 cents is 5/20
thus the possibilty of 2 coins summing to 25 cents is 1 in 6