Salim and Bryan are out riding, on an errand for Al Khalil, when they see the [wolf] that has been terrorizing a nearby village. They pull to a halt and Bryan aims his bow at the creature.
The wolf is not moving, at a distance of about 30 paces. This is an easy shot, with an ease factor of 9+. However, since he is on horseback there is a +2 penalty, increasing the difficulty to 11+. He rolls a 10 and misses.
The wolf is startled and flees, Salim urges his horse into a gallop and pursues. The wolf is still within 50 paces, but it is now dodging, so it is now a hard shot with an ease factor of 15+.
Because Salim is shooting from a moving mount, the difficulty should increase by 15 to 30+. However, Salim is a trained horse archer, to his total ease factor is 15 + (15/2) = 22. He gets lucky and rolls two 1's and a 6, hitting the wolf.