Answer
$x=70.42~cm$
Work Step by Step
$p(z\gt z_0)=p(z\gt0)-p(0\lt z\lt z_0)=.5-p(0\lt z\lt z_0)=.1$
$p(0\lt z\lt z_0)=.4$
If $p(0\lt z\lt z_0)=.4$ then $z_0=1.28$
$z_0=\frac{x-\mu}{\sigma}$
$1.28=\frac{x-55.7}{11.5}$
$x=55.7+1.28(11.5)=70.42$