Q: Solve:
Solve 0 = 195*r - 189*r + 6 for r.

A: -1

Q: Solve:
Solve -1269278*o + 1269514*o + 20296 = 0 for o.

A: -86

Q: Solve:
Solve -1277*d = -1108*d - 3549 for d.

A:
21