Steven ran 15 miles in 8 minutes.
so, the unit rate = distance over the time
So, the unit rate for Steven = 15/8 = 1.875 miles/minutes
Jackson ran 20 miles in 11 minutes
so, the unit rate for Jackson = 20/11 = 1.818 miles/minutes
By comparing the numbers 1.875 and 1.818
So, 1.875 > 1.818
So, the unit rate of Steven > unit rate of Jackson
so, the faster is Steven