\(20-\left\{12+\left[24-3.\left(2+5\right)\right]\right\}\)
\(=20-\left\{12+\left[24-3.7\right]\right\}\)
\(=20-\left\{12+\left[24-21\right]\right\}\)
\(=20-\left\{12+3\right\}\)
\(=20-15\)
\(=5\)
\(#Wendy.Dang\)
\(20-\left\{12+\left[24-3.\left(2+5\right)\right]\right\}\)
\(=20-\left\{12+\left[24-3.7\right]\right\}\)
\(=20-\left\{12+\left(24-21\right)\right\}\)
\(=20-\left(12+3\right)\)
\(=20-15=5\)