a) \(27\cdot75+25\cdot27-150\)
\(=27\cdot\left(75+25\right)-150\)
\(=27\cdot100-150\)
\(=2700-150\)
\(=2550\)
b) \(12:\left\{390:\left|500-\left(125+35\cdot7\right)\right|\right\}\)
\(=12:\left\{390:\left|500-\left(125+245\right)\right|\right\}\)
\(=12:\left\{390:\left|500-370\right|\right\}\)
\(=12:\left\{390:130\right\}\)
\(=12:3\)
\(=3\)