Answer:
168 : 1675
Step-by-step explanation:
At the beginning of the race, the number of ratio units was 2+19 = 21, so each stands for 4200/21 = 200 participants. Then there were ...
- 2×200 = 400 runners
- 19×200 = 3800 joggers
At the end of the race, there were 450 fewer joggers, so ...
3800 -450 = 3350 . . . joggers
16% of the 400 runners is 64 runners, so with that many dropping out, the remaining number of runners was ...
400 -64 = 336
So, at the end of the race the ratio of runners to joggers was ...
336 : 3350 = 168 : 1675