Q: Solve -465*r - 405*r = 138*r + 7056 for r.

A: -7

Q: Solve 0 = -7*a + 10*a - 15 for a.

A: 5

Q: Solve 0 = -421*t - 16367 - 52 for t.

A: -39

Q: Solve -15 = -32*x + 37*x - 100 - 230 for x.

A:
63