Q: What is the solution?
Solve -y = 30 - 29 for y.

A: -1

Q: What is the solution?
Solve 42791569*r - 42791465*r + 1560 = 0 for r.

A: -15

Q: What is the solution?
Solve -643*r = -285*r - 269*r - 2047 for r.

A:
23