Question:
Solve 0 = -v - 9 + 14 for v..

Answer:
5

Question:
Solve -200 = -13*c - 278 for c..

Answer:
-6

Question:
Solve -13*d = -7*d + 12 for d..

Answer:
-2

Question:
Solve 207110 + 75035 = 2750*r + 64895 for r..

Answer:
79