Question: What is the solution?

Solve 30 = 13*u - 0*u - 7*u for u.

Answer: 5

Question: What is the solution?

Solve 15 = -6*r - 9 for r.

Answer: -4

Question: What is the solution?

Solve -805*t + 35275 = -40395 for t.

Answer: 94

Question: What is the solution?

Solve -42699*x = -42700*x - 42 for x.

Answer:
-42