Answer:
1 song costs $1.21
Step-by-step explanation:
The distance between the number of songs for 16 and 18 is 2, and the same from 18 to 20. So with this we can find the difference between the costs correlated with these amounts of songs and divide by 2 to get the cost per song.
21.78 - 19.36 = 2.42
24.20 - 21.78 = 2.42
2.42 / 2 = 1.21
This means for every 1 song bought, you pay $1.21
