Q: Solve:
Solve 18*d + 31*d = -54*d + 515 for d.

A: 5

Q: Solve:
Solve 18*k + 506 = 812 for k.

A: 17

Q: Solve:
Solve 25900*u - 25408*u - 6527 = 853 for u.

A:
15