Answer:
21 songs
Step-by-step explanation:
Let's figure out how many are R&B songs first.
We know that 1/4 of the 28 total songs are R&B. Remember that in mathematics, "of" usually means to multiply, so we multiply 1/4 by 28:
1/4 * 28 = 7 songs
So, 7 songs are R&B. This means that since the rest are rap, we can subtract 7 from the total 28:
28 - 7 = 21 songs
