c) 1 3/5 - (30% - 5/2). 3/4

* Hướng dẫn giải

c) $1\frac{3}{5}-\left(30\%-\frac{5}{2}\right).\frac{3}{4}$

$$\begin{gathered} =\frac{5.1+3}{5}-\left(\frac{3}{10}-\frac{5}{2}\right).\frac{3}{4} \\ =\frac{8}{5}-\left(\frac{3}{10}-\frac{5.5}{5.2}\right).\frac{3}{4} \\ =\frac{8}{5}-\left(\frac{3}{10}-\frac{25}{10}\right).\frac{3}{4} \\ =\frac{8}{5}-\frac{-22}{10}.\frac{3}{4} \\ =\frac{8}{5}-\frac{-11.2}{5.2}.\frac{3}{4} \\ =\frac{8}{5}-\frac{-33}{20} \\ =\frac{8.4}{5.4}-\left(-\frac{33}{20}\right) \\ =\frac{32}{20}+\frac{33}{20} \\ =\frac{65}{20} \\ =\frac{13.5}{4.5} \\ =\frac{13}{4} \end{gathered}$$