Thực hiện phép tính: a) 6 5/12 : 2 3/4 + 11 1/4 (1/3 - 1/5) b) 1 13/15 .0,75

* Hướng dẫn giải

a) 

$\begin{array}{l}6\frac{5}{12}:2\frac{3}{4}+11\frac{1}{4}\left(\frac{1}{3}-\frac{1}{5}\right)\\ =\frac{77}{12}:\frac{11}{4}+\frac{45}{4}.\frac{2}{15}\\ =\frac{7}{3}+\frac{3}{2}\\ =\frac{23}{6}\end{array}$

b) 

$\begin{array}{l}1\frac{13}{15}\cdot 0,75-\left(\frac{11}{20}+25\%\right):\frac{7}{5}\\ =\frac{28}{15}\cdot \frac{3}{4}-\left(\frac{11}{20}+\frac{1}{4}\right):\frac{7}{5}\\ =\frac{7}{5}-\frac{4}{5}\cdot \frac{5}{7}\\ =\frac{7}{5}-\frac{4}{7}\\ =\frac{29}{35}\end{array}$