To find height $ h $ use formula:
$$ A = a \cdot h $$After substituting $A = 110.7\, \text{cm}$ and $a = 12.3\, \text{cm}$ we have:
$$ 110.7\, \text{cm} = 12.3\, \text{cm} \cdot h $$$$ h = \dfrac{ 110.7\, \text{cm} }{ 12.3\, \text{cm} } $$$$ h = 9 $$