Answer:
C
Step-by-step explanation:
4 - 5 = -1
Count:
4, 3, 2, 1, 0, <u>-1</u>
-2(7-15) / 4
-2(-8) = 16
16/4 = 4
Answer is 4
1, 6, 15, 20, 15, 6, 1