a)

Since Bryston ran only 7/8 of the distance, he had 1/8 more to run to finish the marathon.

If he ran 7/8 of the distance in 42 minutes,
then for 1/8 of the distance, he takes :

42min ÷ 7 = 6min

So he needs to run for 6 more minutes.

42 minutes + 6 minutes = 48 minutes

Since they started at 8.00am,

0800 + 0048 = 0848

Bryston will finish at 8.48am.







b)

Since Akash is 35m/min faster than Bryston,

Every minute, he runs 35m more than Bryston.

In 42 minutes,
42 x 35m = 1470m

He finished the marathon and ran 1470m more than Bryston. So Bryston had 1470m more to run to finish it.

Since Bryston had 1/8 of the distance left to run, this also tells you that 1470m is 1/8 of the marathon distance.


Entire marathon distance = 1470m x 8 = 11760m

Akash's average speed = 11760m ÷ 42min
= 280m/min