\(76-\left\{2\cdot\left[2\cdot5^2-\left(31-2\cdot3\right)\right]\right\}\)
\(=76-\left\{2\cdot\left[2\cdot25-\left(31-6\right)\right]\right\}\)
\(=75-\left[2\cdot\left(50-25\right)\right]\)
\(=76-\left(2\cdot25\right)\)
\(=76-50\)
\(=26\)
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\(6^2\cdot10:\left\{780:\left[10^3-\left(2\cdot5^3+35\cdot14\right)\right]\right\}\)
\(=36\cdot10:\left\{780:\left[1000-\left(2\cdot125+490\right)\right]\right\}\)
\(=360:\left\{780:\left[1000-\left(250+490\right)\right]\right\}\)
\(=360:\left[780:\left(1000-740\right)\right]\)
\(=360:\left(780:260\right)\)
\(=360:3\)
\(=120\)
a: =76-{2*[2*25-31+6]}
=76-{2*[50-31+6]}
=76-2*25
=76-50=26
b: \(=360:\left\{\dfrac{780}{1000-2\cdot125-490}\right\}\)
\(=360:\dfrac{780}{260}\)
=360/3=120