Q: What is the solution?
Solve 18 = -30*r + 27*r for r.

A: -6

Q: What is the solution?
Solve -46*f + 16*f + 159 - 39 = 0 for f.

A: 4

Q: What is the solution?
Solve 20*d = -9 + 33 + 36 for d.

A:
3