\(100:\left\{250:\left[450-\left(4.5^3-2^5.25\right)\right]\right\}\)
\(=100:\left\{250:\left[450-\left(500-800\right)\right]\right\}\)
\(=100:\left\{250:\left[450+300\right]\right\}\)
\(=100:\left\{250:700\right\}\)
\(=100:\frac{5}{14}\)
\(=280\)
100:{250:[450 - ( 4 . 125 - 4.25 )]}
100: { 250: [ 450 - ( 500 - 100 ) ]}
100: {250:[ 450 - 400]
100: { 250 : 50 }
100: 5 = 20