The first part is okay.

ii. How far had A run when he first overlapped B?

Rate of A = 10,000 /800.4 = 12.49375 m/sec

Rate of B = 10,000 /937 = 10.67236 m/sec

A had run 1 more lap than B when he overtook B, so,

12.49375(t) = 10.67236(t) +400

t = 400 /(12.49375 -10.67236) = 219.61249 sec.

Hence, A ran

(12.49375 m/sec)(219.61249 sec) = 2743.78 meters -------answer.

... when he caught up with B for the first time

----------------------

iii. How many times was B lapped?

From part (ii) above, A overlapped B every 2743.78 meters, so,

10,000 /2743.78 = 3.6446

Meaning, A overlapped B, 3 times --------------answer.