a.
\(\left[3\times\left(-2\right)-\left(-8\right)\right]\times\left(-7\right)-\left(-2\right)\times\left(-5\right)=\left(-6+8\right)\times\left(-7\right)-10=2\times\left(-7\right)-10=-14-10=-24\)
b.
\(85\times\left(35-27\right)-35\times\left(85-27\right)=85\times35-85\times27-35\times85+35\times27=\left(85\times35-35\times85\right)-27\times\left(85-35\right)=-27\times50=-1350\)
c.
\(\left(20\times2^4-12\times2^3-48\times2^2\right)^2\div\left(-8\right)^2=\left(\frac{5\times4\times2^4-3\times4\times2^3-3\times16\times2^2}{-8}\right)^2=\left(\frac{5\times2^2\times2^4-3\times2^2\times2^3-3\times2^4\times2^2}{\left(-2\right)^3}\right)^2\)\(=\left(\frac{2^5\times\left(5\times2-3-3\times2\right)}{-\left(2^3\right)}\right)^2=\left(-2^2\right)^2=16\)
