Question:
Solve -3*r - 14 = -10*r for r..

Answer:
2

Question:
Solve -86*l + 637 + 1096 = -1965 for l..

Answer:
43

Question:
Solve -142 = 20*u - 29*u + 65 for u..

Answer:
23

Question:
Solve -380*v - 711 - 1144 = -327*v for v..

Answer:
-35