Answer:
5 pennies, 14 nickels, 21 dimes, 10 quarters (Sorry I don't know how much each coin is worth)
Explanation:
10% of 50 = 0.1 * 50 = 5 pennies
42% of 50 = 0.42 * 50 = 21 dimes
9 more nickels than pennies = 5 + 9 = 14 nickels
50 - 5 - 21 - 14 = 10 quarters