\(\left(\frac{3}{20}+\frac{1}{2}-x\right):\frac{32}{9}=\frac{21}{128}\)
\(\left(\frac{13}{20}-x\right):\frac{32}{9}=\frac{21}{128}\)
\(\frac{13}{20}-x=\frac{21}{128}\times\frac{32}{9}\)
\(\frac{13}{20}-x=\frac{7}{12}\)
\(x=\frac{13}{20}-\frac{7}{12}\)
\(x=\frac{1}{15}\)
( 3/20 + 1/2 - x ) : 32/9 = 21/128
3/20+ 1/2 - x = 21/128 x 32/9
13/20 - x = 7/12
x = 13/20 - 7/12
x = 1/15