Answer:
18.
Step-by-step explanation:
If there were 90 runners, and in the first half 2/5 of them dropped out, here's how we get those who continued the race in the second half.
1. Firstly we need to calculate how many of them dropped out:
2/5 of 90 = 90 ÷ 5 × 2
2/5 of 90 = 18 × 2
2/5 of 90 = 36
2. Now we have to take away the number of dropped-out runners from the total number of runners from the beginning of the race:
90 - 36 = 54
Now we are left with 54 runners, 2/3 of which dropped out before the finish line.
1. In order to get the number of runners that finished the race, we first need to see how many of them gave up in the second half:
2/3 of 54 = 54 ÷ 3 × 2
2/3 of 54 = 18 × 2
2/3 of 54 = 36
2. Now we just take away the number of runners that dropped out in the second half from the number on the beginning of the half:
54 - 36 = 18
18 runners finished the race.
