`13/20-(1/4-5/20)`
`=13/20-1/4+5/20`
`=18/20-1/4`
`=18/20-5/20`
`=13/20`
\(\dfrac{13}{20}-\left(\dfrac{1}{4}-\dfrac{5}{20}\right)=\dfrac{13}{20}-\dfrac{5}{20}+\dfrac{5}{20}=\dfrac{13}{20}\)
\(\dfrac{13}{20}-\left(\dfrac{1}{4}-\dfrac{5}{20}\right)\)\(=\dfrac{13}{20}-\left(\dfrac{1}{4}-\dfrac{1}{4}\right)\)\(=\dfrac{13}{20}-0=\dfrac{13}{20}\)