Please help me with this problem I been stuck in this problem for 45 min and don't know how to go about it ????

5. True or false, and explain: (a) If a die is rolled 5 times, the chance of getting at least one ace is 1/6 + 1/6 + 1/6 + 1/6 + 1/6 + 1/6 -5/6. (b) If a coin is tossed twice, the chance of getting at least one ace is 100%