Answer:
12 bikers are required.
Explanation:
Each Biker has to ride 50 miles
Let number of bikers be x
so total travel by x bikers = 50 multiplied by x = 50x
According to the question
50x = 560
Dividing both sides by 50 ,we get

x = 11.2
Since number of bikers cannot be in in decimals
therefore it is 12
12 bikers are required.