Ответ:

\(\frac14+\frac3{50}-\frac7{20}+\frac8{20}=\frac{50+12-70+80}{200}=\frac{72}{200}=\frac9{25}=0.36\).

\(\frac45-\frac12=\frac8{10}-\frac5{10}=\frac3{10}=0.3\).

\(\frac{17}{40}-\frac{11}{200}=\frac{85-11}{200}=\frac{74}{200}=\frac{37}{100}=0.37\).

Ответ: \(\frac9{25}=0,36;\ \frac3{10}=0,3;\ \frac{37}{100}=0,37\).