Which mathematical sentence most accurately expresses the information in the problem below?
crystal has 100 compact discs that she wants to put into boxes each of the boxes that she brought home holds 15 discs how many of these boxes will she need for all of her disks?
a: 100-b=15
b: b+15=100
c: 15b< 100
d: 15b> (or equal to) 100