The answer is
a. FeCl3 + 3 NaOH = Fe(OH)3 + 3 NaCl
b. 2 C2H2 + 5 O2 = 4 CO2 + 2 H2O
c. Fe2O3 + 3 H2 = 2 Fe + 3 H2O
To balance equations you basically have to make sure each element has an equal amount or number on each side of the equation. If you need more help understanding this, feel free to ask.
:)