You add 10 to -7 to get 3.
7
-17
3
Starting with 85, if you add 7, you get 92. Then, if you increase the number you add by 3 each time, you would add 10 (7+3) to 92, resulting in 102. Continuing this pattern, you would add 13 (10+3) to 102, resulting in 115, and so on.
-25
10
4
The number is 21. 21 ÷ 3 = 7 7 - 3 = 4
256
10
3