Emily and Frank shared a cake with 16 equally-sized slices. Emily wanted a plain cake, but Frank wanted chocolate frosting on one-quarter of the cake. The cost of a plain cake was $16, and there was an additional cost of $4 for putting chocolate frosting on one-quarter. Frank ate all of the slices with chocolate frosting and five plain slices. Emily ate the remainder. Each then paid for what he or she had eaten. How many more dollars did Frank pay than Emily?