a,2/3+3/4+7/2 b,2 1/3+2/3.(-4/3+1/6):5/6 c, 5/7.19/26+5/7.18/26-5/14.11/13

a, $\dfrac{2}{3}$ + $\dfrac{3}{4}$ + $\dfrac{7}{2}$ 

= $\dfrac{2}{3}$ + ( $\dfrac{3}{4}$ + $\dfrac{7}{2}$ )

= $\dfrac{2}{3}$ + $\dfrac{17}{4}$

= $\dfrac{59}{12}$ 

b, $2$ . $\dfrac{1}{3}$( cái này bị sai đề bạn nha ) + $\dfrac{2}{3}$ . ( $\dfrac{-4}{3}$ + $\dfrac{1}{6}$ ) : $\dfrac{5}{6}$ 

= $\dfrac{2}{3}$ + $\dfrac{2}{3}$ . $\dfrac{-7}{6}$  : $\dfrac{5}{6}$

= $\dfrac{2}{3}$ + $\dfrac{2}{3}$ . ( $\dfrac{-7}{6}$  : $\dfrac{5}{6}$ ) = $\dfrac{2}{3}$ + $\dfrac{2}{3}$ . $\dfrac{-7}{5}$ = $\dfrac{2}{3}$ . ( $1$ + $\dfrac{-7}{5}$ )

= $\dfrac{2}{3}$ . $\dfrac{-2}{5}$ =$\dfrac{-4}{15}$ 

c, $\dfrac{5}{7}$ . $\dfrac{19}{26}$ + $\dfrac{5}{7}$ . $\dfrac{18}{26}$ – $\dfrac{5}{14}$ . $\dfrac{11}{13}$

= $\dfrac{5}{7}$ . ( $\dfrac{19}{26}$ +  $\dfrac{18}{26}$ ) – $\dfrac{5}{14}$ . $\dfrac{11}{13}$

= $\dfrac{5}{7}$ . $\dfrac{27}{26}$ – $\dfrac{5}{14}$ . $\dfrac{11}{13}$

= $\dfrac{5}{7}$ . $\dfrac{27}{26}$ – $\dfrac{5}{7}$ . $\dfrac{1}{2}$ .  $\dfrac{11}{13}$

= $\dfrac{5}{7}$ . ( $\dfrac{27}{26}$ – $\dfrac{1}{2}$ .  $\dfrac{11}{13}$ ) = $\dfrac{5}{7}$ . ( $\dfrac{27}{26}$ – $\dfrac{11}{26}$ ) = $\dfrac{5}{7}$ . $\dfrac{8}{13}$ = $\dfrac{40}{91}$ 

# Try _ hard _ together