Q: Solve 854942*a - 18870 = 854757*a for a.

A: 102

Q: Solve 21*i = 5*i + 80 for i.

A: 5

Q: Solve -129*r - 542 = 748 for r.

A: -10

Q: Solve 0 = -411*n - 8757 - 7272 for n.

A:
-39