Question

Tính.

\(\dfrac{5}{7}+\dfrac{3}{4}\)                   \(\dfrac{4}{9}+\dfrac{2}{7}\)                  \(\dfrac{4}{5}-\dfrac{2}{3}\)                   \(\dfrac{5}{9}-\dfrac{3}{8}\)

Answer 1

$\frac{5}{7} + \frac{3}{4} = \frac{{20}}{{28}} + \frac{{21}}{{28}} = \frac{{41}}{{28}}$   

$\frac{4}{9} + \frac{2}{7} = \frac{{28}}{{63}} + \frac{{18}}{{63}} = \frac{{46}}{{63}}$   

$\frac{4}{5} - \frac{2}{3} = \frac{{12}}{{15}} - \frac{{10}}{{15}} = \frac{2}{{15}}$           

$\frac{5}{9} - \frac{3}{8} = \frac{{40}}{{72}} - \frac{{27}}{{72}} = \frac{{13}}{{72}}$