Q: Solve:
Solve 21*k = 9*k - 12 for k.

A: -1

Q: Solve:
Solve 0 = 48*i - 44*i + 16 for i.

A: -4

Q: Solve:
Solve 3898*r + 2512*r + 3512*r = -793760 for r.

A:
-80