Question 100321
Let the walking rate be x(km/h).

This means that after 1 hour she has walked x km.
So after 2 hours she will have walked 2x km.

We are told that she then cycles at three times her walking rate.
This means that her cycling rate =3*x=3x(km/h).
But we are told that she only cycles for 1/3 of an hour and so her cycling distance is 1/3 of 3x km. which is 1x or x km.

So she walks 2x km and cycles x km,giving a total travelling distance of 3x km. 

But we are told that the total distance travelled is 12km.

                          Hence 3x=12.

Now share each side of this equation by 3 and we get:

                                 x=4.

So her walking rate is 4km/h.ANS
(NB. In English English we usually say "cycled" rather than "bicycled" and we spell the US "traveled" as "travelled"!).