Correct Answer: 77.5 seconds

Solution : Given: In a 200 m linear race, if A gives B a start of 25 m, A wins by 10 seconds.
Alternatively, if A gives B a start of 45 m, the race ends in a dead heat.
So, the additional 20 m start given to B compensates for the 10 seconds.
i.e., B runs 20 m in 10 seconds.
Hence, B will take 100 seconds to run 200 m.
Also, A gives B a start of 45 m.
Since B runs 20 m in 10 seconds, 45 m will be covered in 22.5 seconds.
A will take 22.5 seconds less than B, or, 100 – 22.5 = 77.5 seconds, to
complete the race.
Hence, the correct answer is 77.5 seconds.