Q: What is the solution?
Solve 21*v = -142 - 43 - 25 for v.

A: -10

Q: What is the solution?
Solve -8040*r + 8020*r - 140 = 0 for r.

A: -7

Q: What is the solution?
Solve 5744 - 4932 + 6307 = 1017*o for o.

A:
7