\(3\cdot5^2-16\cdot2^2\)
\(=3\cdot25-16:4\)
\(=75-4\)
\(=71\)
==============
\(2^3\cdot17-2^3\cdot14\)
\(=2^3\cdot\left(17-14\right)\)
\(=2^3\cdot3\)
\(=8\cdot3\)
\(=24\)
===============
\(15\cdot141+59\cdot15\)
\(=15\cdot\left(141+59\right)\)
\(=15\cdot200\)
\(=3000\)
================
\(17\cdot85+15\cdot17-120\)
\(=17\cdot\left(85+15\right)-120\)
\(=17\cdot100-120\)
\(=1700-120\)
\(=1580\)
===============
\(20-\left[30-\left(5-1\right)^2\right]\)
\(=20-\left(30-4^2\right)\)
\(=20-\left(30-16\right)\)
\(=20-14\)
\(=6\)