Level 3 Adrian had 3 coins and Alex had 6 coins. Their coins consisted of 20¢ coins and 50¢ coins. When all their 50¢ coins were exchanged for 20¢ coins, they had a total of 15 coins. How many 20¢ coins did they have at first?
Level 1
In the 5-digit number, 8 ___ 542, the difference between the value of the digit 8 and the value of the missing digit is 77000. What is the missing digit?