12:{390:[500-(5^3+5.7^2) ] }
=12:{390:[500-(125+245 ) ] }
=12:{390:[500-370] }
=12:{390:130}
=12:3
=4
\(12:\left\{390:\left[500-\left(5^3+5.7^2\right)\right]\right\}\)
\(=12:\left\{390:\left[500-\left(125+5.49\right)\right]\right\}\)
\(=12:\left\{390:\left[500-\left(125+245\right)\right]\right\}\)
\(=12:\left\{390:\left[500-370\right]\right\}\)
\(=12:\left\{390:130\right\}\)
\(=12:3\)
\(=4\)
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