Answer:
24 runners
Step-by-step explanation:
If 1/4 of the runners dropped out, then 1 - 1/4 or 3/4 continued on. 3/4 of 56 or 3/4 *56 is 42 runners left. Then, out of these 42, 3/7 dropped out. This means 1 - 3/7 or 4/7 of the runners remained. This means that 4/7 * 42 or 24 runners finished the race.