question: Teacher asked me this: Solve -4*x = -11*x - 28 for x.
++++++++++
answer: -4

question: Teacher asked me this: Solve -3 = -721*o + 724*o for o.
++++++++++
answer: -1

question: Teacher asked me this: Solve 0 = 2*f - 4*f - 6 for f.
++++++++++
answer: -3

question: Teacher asked me this: Solve 0 = d + 7*d for d.
++++++++++
answer:
0