The only two coins that add up to 26 cents are a penny and a quarter.
That leaves 1 quarter, 5 dimes, 3 nickles, and 3 pennies in the bag.
probability = number of pennies in bag / total number of coins
probability = 3 / (1 + 5 + 3 + 3)
probability = 3 / 12
probability = 1 / 4