We are given the values of $20 and $1.29.
Then, we were given the variable m, representing the number of songs downloaded.
First, figure out where the variable m is supposed to go. If m indicates the amount of songs downloaded, then it would make sense to group it with $1.29 because that is the value of each song. It would not make sense to group it with $20 because that is the value of how much Mariana has, not how much she will spend.
So now we know it is $1.29m, let us determine which inequality sign we need. We can figure this out simply by using context. If Mariana had a $20 gift card, she could not go over that amount in spending; however, she could go under that amount or exactly that amount. This indicates that $1.29m must be less than or equal to 20.
Therefore. The answer is C because it states that 1.29m is less than or equal to 20.
If this is wrong, I apologize, and please ask me any questions if you have them.