The answer is: 30 Trips
Total fans = 100,000
The amount of fans that need satelite parking
= 100,000 x 42%
= 42,000 fans
There are 20 buses and each of them can carry 70 fans in one trip. So the maximum number of fans that all of them can carry in one trip:
= 70 x 20
= 1400 fans
Total trips that each bus need to take all fans to stadium
= 42,000 / 1400
= 30 trips