3. Two racers with speeds of $100 \mathrm{~m} / \mathrm{c}$ and $70 \mathrm{~m} / \mathrm{c}$ started simultaneously in the same direction from the same place on a circular track of length $800 \mathrm{m}$. How many times did the racers meet after the start if both drove for 320 seconds?
Answer: 12

## Examples of writing answers:

45

## Problem 4 (2 points).