Question:
Solve -91*v + 39*v = 119*v - 6498 for v..

Answer:
38

Question:
Solve r + 13 = 10 for r..

Answer:
-3

Question:
Solve 0 = 31*a - 38*a + 42 for a..

Answer:
6

Question:
Solve -54 = 4*u + 8*u - 6*u for u..

Answer:
-9