let robert bicycles at speed = x km/h.

then, speed of jodie will be = (x+5)km/h.

say time = t hrs (for both of them).

also, its given that, in same time robert bicycles 48 km.

i.e    x*t =48         ........ eq 1.

and, distance travelled by jodie =  (x+5)*t ....... eq 2.

now, say the difference in distance travelled by both of them(say, d) in time t = (x+5)*t - x*t

                                                                                             d  = 5*t. 

and,its given that difference in their speed(say s) = 5.

so, difference of time that robert needed to travel the same distance that jodie does is = d/s

i.e = 5*t/5 = t.

now, this means it will require the same amount of time more for robert to travel the distance which jodie have already done.

i.e jodie bicycles with twice the speed than robert.

i.e, (x+5) =2x 

i.e x = 5 km/h(roberts speed)

and, jodie speed =x+5 =10km/h Ans.