question: Teacher asked me this: Solve 137*s - 123*s + 84 = 0 for s.
++++++++++
answer: -6

question: Teacher asked me this: Solve 0 = -30*o + 42*o + 72 for o.
++++++++++
answer: -6

question: Teacher asked me this: Solve 0 = -57*a + 27*a for a.
++++++++++
answer: 0

question: Teacher asked me this: Solve -1462*u + 800 = -1502*u for u.
++++++++++
answer:
-20