Đáp án:
$\begin{array}{l}
a)\left( { - 53} \right) + 36 + \left( { - 39} \right) + 42 + \left( { - 45} \right) + 48\\
= \left( { - 53} \right) - 3 - 3 + 48\\
= \left( { - 53} \right) + 48 - 6\\
= - 53 + 42\\
= - \left( {53 - 42} \right)\\
= - 11\\
b)\left( {{3^5}.27 - {2^{15}}.2} \right):{3^{18}}\\
= \left( {{3^5}{{.3}^3} - {2^{16}}} \right):{3^{18}}\\
= {3^8}:{3^{18}} - {2^{16}}:{3^{18}}\\
= \frac{1}{{{3^{10}}}} - \frac{{{2^{16}}}}{{{3^{18}}}}\\
c) - 2989 + \left( { - 989 - \left( {297:{3^2} + {2^2}{{.3}^3}} \right)} \right)\\
= - 2989 + 989 + \left( {297:9 + 4.27} \right)\\
= - 2000 + 33 + 108\\
= - 2000 + 141\\
= - 1859
\end{array}$
