Question:
Solve -90*n = -67*n + 69 for n..

Answer:
-3

Question:
Solve 41*m - 4097 = -3687 for m..

Answer:
10

Question:
Solve -2*u - 29 - 66 = -7*u for u..

Answer:
19

Question:
Solve -316*r - 70 - 2323 + 1100 = 3131 for r..

Answer:
-14