Let the sum of hight of the other 2 buildings be x. So their \(\displaystyle\mu=\frac{{x}}{{2}}.\)

\(\displaystyle\frac{{{58}+{55}+{53}+{x}}}{{5}}={56}\)

\(\displaystyle\frac{{{166}+{x}}}{{5}}={56}\)

\(\displaystyle{166}+{x}={280}\)

\(\displaystyle{x}={114}\)

Substitute to \(\displaystyle\mu=\frac{{x}}{{2}}.\)

\(\displaystyle\mu=\frac{{114}}{{2}}\)

\(\displaystyle\mu={57}\) m

\(\displaystyle\frac{{{58}+{55}+{53}+{x}}}{{5}}={56}\)

\(\displaystyle\frac{{{166}+{x}}}{{5}}={56}\)

\(\displaystyle{166}+{x}={280}\)

\(\displaystyle{x}={114}\)

Substitute to \(\displaystyle\mu=\frac{{x}}{{2}}.\)

\(\displaystyle\mu=\frac{{114}}{{2}}\)

\(\displaystyle\mu={57}\) m