Riley and Magdalena bought beads to make a necklace. The beads that Riley bought cost ¢48 for 12. Magdalena bought 20 beads for $1.00. How much less does 15 of rileys beads cost than 15 of Magdalenas beads?

Riley : 0.48/12 = 0.04 per bead

Magdalena : 1.00/20 = 0.05 per bead

15 beads ...

Riley : 15 x 0.04 = 0.60

Magdalena : 15 x 0.05 = 0.75

15 of Riley's beads cost (0.75 - 0.60) = 0.15 cents less then 15 of Magdalena's beads