Answer:
1 1/3 more minutes
Explanation:
Lets first convert both times to improper fractions
7 1/2 -> 15/2 (Mark's Time)
6 1/6 -> 37/6 (Mark's Brother's Time)
Now we need common denominators
15/2 = 45/6
Now times to subtract Mark's time - Mark's Brother's Time = More Time
45/6 - 37/6 = 8/6 or 1 2/6 = 1 1/3