first you will subtract 12.99 from 50
50 - 12.99 = 37.01
now you need to divide 16 by 12.99 to find out how much it costs for a single song
16 divided by 12.99 = $1.23
now you will divide 37.01 divided by 1.23
37.01 divided by 1.23 = about 30
this means youll get about 30 single tracks with your gift card.
let me know if you have any further questions
:)