a)\(\left(\dfrac{4}{6}+\dfrac{14}{6}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)+\left(\dfrac{17}{9}+\dfrac{1}{9}\right)=\dfrac{18}{6}+\dfrac{26}{13}+\dfrac{18}{9}=3+2+2=7\)
b)\(\dfrac{6}{7}+\left(\dfrac{2}{1}-\dfrac{6}{7}\right)=\dfrac{6}{7}+\left(\dfrac{14}{7}-\dfrac{6}{7}\right)=\dfrac{6}{7}+\dfrac{8}{7}=\dfrac{14}{7}=2\)
c)\(\dfrac{2}{3}\times\left(\dfrac{15}{19}+\dfrac{4}{19}\right)=\dfrac{2}{3}\times\dfrac{19}{19}=\dfrac{2}{3}\times1=\dfrac{2}{3}\)
a)(46+146)+(713+1913)+(179+19)=186+2613+189=3+2+2=7(46+146)+(713+1913)+(179+19)=186+2613+189=3+2+2=7
b)67+(21−67)=67+(147−67)=67+87=147=267+(21−67)=67+(147−67)=67+87=147=2
c)