If you are willing to assume that the parameters are real valued:

FindInstance[x + y - Log[z + a] (b + c) \[Element] Reals, {x, y, z, a, b, c} \[Element] Reals]

If you are willing to assume that the parameters are real valued:

FindInstance[x + y - Log[z + a] (b + c) \[Element] Reals, {x, y, z, a, b, c} \[Element] Reals]

Or you can get a fuller account:

Reduce[x + y - Log[z + a] (b + c) \[Element] Reals, {x, y, z, a, b, c} \[Element] Reals]