Final answer:
To find out how much longer Amelia needs to be, subtract the length of her song from the desired length of the performance. The answer is 1 1/2 minutes.
Step-by-step explanation:
To find out how much longer Amelia needs to be, we need to subtract the length of her song from the desired length for the performance. Amelia's song is currently 3/4 of a minute long, and she wants her performance to be 2 1/4 minutes long. To find out how much longer she needs to be, we subtract 3/4 from 2 1/4:
2 1/4 - 3/4 = 2 - 3/4 = 2 - 0.75 = 1.25 minutes
So, Amelia needs to be 1 1/4 minutes longer. Therefore, the answer is c) 1 1/2 minutes.