Answer is: Scott rode faster than Jill.
t(Jill, Scott) = 30 min ÷ 60 min/h.
t(Jill, Scott) = 0.5 h; Jills and Scott time.
d(Jill) = 5 km; Jills traveled distance.
s(Jill) = d(Jill) ÷ t(Jill).
s(Jill) = 5 km ÷ 0.5 h.
s(JIll) = 10 km/h; Jills speed.
s(Scott) = 10 km ÷ 0.5 h.
s(Scott) = 20 km/h; speed of Scott.