Answer:
4x + 19 = -21
Step-by-step explanation:
4(-10) + 19 = -21
-40 + 19 = -21
The numbers:
1, -3, 2, -9, 3, -15, 4, -21,
are not linear.
If it was linear:
4, 3, 2, 1, -3, -9, -15, -21