6.1 Three people with one double seater motorbike simultaneously headed from city A to city B . How should they act so that time, for which the last of them will get to , was the smallest? Determine this time. Pedestrian speed - 5 km/h, motorcycle speed - 45 km/h, distance from A to B is equal to 60 kilometers .
6.2 / 7.2 The numbers A and B are relatively prime. What common divisors can have the numbers A+B and A−B?
6.3. A person's age in 1962 was one more than the sum of digits of the year of his birth. How old is he?
6.4. / 7.3 15 magazines lie on the table, completely covering it. Prove that it is possible to remove eight of them so that the remaining magz cover at least 7/15 of the table area.
6.5. Prove that a 201×201 chessboard can be bypassed by moving a chess knight, visiting each square exactly once.
6.6. Can an integer whose last two digits are odd be the square of another integer?
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