Question:
Solve -9*a + 10*a + 1 = 0 for a..

Answer:
-1

Question:
Solve 12*r = 9*r + 6 for r..

Answer:
2

Question:
Solve -2*l = -28 + 16 for l..

Answer:
6

Question:
Solve 86*s + 540 = -22*s for s..

Answer:
-5