18 . { 420 : 6 - [ 150 - ( 68 . 2 - 23 . 5)]}
= 18{70+[150-(136-8.5)]}
= 18{70+[150-(136-40)]}
= 18.[70+(150-96)]
= 18.(70+54)
=18.124
=2232.
\(=18\cdot\left\{70-\left[150-\left(136-40\right)\right]\right\}\)
\(=18\cdot\left\{70-\left[150-96\right]\right\}\)
\(=18\cdot\left\{70-54\right\}\)
\(=18\cdot16=288\)