Q: Solve:
Solve 119*r = 549*r - 28*r + 486*r + 20424 for r.

A: -23

Q: Solve:
Solve 0 = -404*a + 402*a - 4 for a.

A: -2

Q: Solve:
Solve 28*v + 25*v = 0 for v.

A:
0