The answer is c.
(a)
x * 2 = y
2 * 2 = 4
3 * 2 = 6
4 * 2 = 8 not 9
(b)
unknown formula
(c)
x * 3 = y
4 * 3 = 12
5 * 3 = 15
6 * 3 = 18
(d)
x * 4
1 * 4 = 4
2 * 4 = 8
3 * 3 = 9 not 15
Answer: No two students ran same distance
Step-by-step explanation:
Given
Stacy ran
of a km i.e.

Jules ran
of a km i.e.

Raul ran
of mile i.e.

So, no two students ran the same distance.
Answer: (19,520-1,478) x 8