This question came from my reader's comment
Distance between Town X and Y is 100km.
At 07:00, Sam left Town X and cycled towards Y.
Ann left Town X and cycled towards Y at 07:30.
Ann's cycling speed was 4 km/h faster than Sam. At 10:00, Ann caught up with Samuel. When Ann was 28 km from town Y, she stopped to wait for Samuel.
(a) How far was Samuel from Ann when she stopped to wait for him?
(b) How many minutes did Ann wait for Samuel?