4OH + Zn+Cu(OH)2→ [Zn(OH)4]2- + Cu + 2OH

Question

how to balanced both side?

Answer 1

4OH + Zn+Cu(OH)2→ [Zn(OH)4]2- + Cu + 2OH

Start by removing the coefficients AND the right hand OH^- AND adding charges like this.
OH^- + Zn + Cu(OH)2→ [Zn(OH)4]^2- + Cu, then
2OH^- + Zn + Cu(OH)2→ [Zn(OH)4]^2- + Cu