Q: Solve -247 = -21*l - 142 for l.

A: 5

Q: Solve -12772*s - 79621 + 21283 = -25739*s + 12504*s for s.

A: 126

Q: Solve 1797*r + 113114 = -509*r + 378304 for r.

A: 115

Q: Solve -147*r + 49*r + 950 = 2237 + 2927 for r.

A:
-43