n a 100 m race, A can give B 10 m and C 28 m. In the same race B can give C:18 m20 m27 m9 m

The problem is about relative speed and distance. Here's how you can solve it:

1. In a 100 m race, A can give B a 10 m lead. This means that when A runs 100 m, B runs 90 m.

2. Similarly, A can give C a 28 m lead. This means that when A runs 100 m, C runs 72 m.

3. Now, we need to find out how much lead B can give C. We know that when A runs 100 m, B runs 90 m and C runs 72 m.

4. So, when B runs 90 m, C runs 72 m.

5. We need to find out how much C would run when B runs 100 m. We can set up a proportion to solve this: 90/72 = 100/x. Solving for x gives us x = 80.

6. Therefore, in a 100 m race, B can give C a 20 m lead.

So, the answer is 20 m.