You have to find the least common multiple (lcm) of 25 and 55.
To find lcm you have to seperate 25 and 55 to prime factors:
25= 5 5
55= 5 11
Both numbers has one same prime factor which is 5 (bolded).
LCM is a multiplication of unique prime factors and one from each pair of the same prime factors, see it below:
\(lcm_{25,55}=5*5*11=275\)
This means that the buses are going to meet at the same stop after 275 minutes from their start.
275 minutes are 4 hours and 35 minutes.
Buses start at 6.00 am, add 4 hours and 35 minutes to receive the time of their meeting which is 10.35 am.
