Write down the solution for this math problem: Solve 42*u - 54*u = -60 for u.
answer: 5

Write down the solution for this math problem: Solve 28 = 13*d + 15 for d.
answer: 1

Write down the solution for this math problem: Solve 1173*t = 1716*t - 4344 for t.
answer: 8

Write down the solution for this math problem: Solve 6*r + 259*r - 156162 - 24480 = -1044*r for r.
answer:
138