a) $\frac{1}{4}$ + $\frac{2}{3}$
=$\frac{3}{12}$ + $\frac{8}{12}$
= $\frac{11}{12}$
b) $\frac{5}{6}$ . $\frac{48}{35}$
= $\frac{8}{7}$
c) $\frac{7}{8}$ : $\frac{10}{9}$ + $\frac{1}{3}$
=$\frac{7}{8}$ . $\frac{9}{10}$ + $\frac{1}{3}$
= $\frac{63}{80}$ + $\frac{1}{3}$
= $\frac{189}{240}$ + $\frac{80}{240}$
= $\frac{260}{240}$ =$\frac{13}{12}$
d) $\frac{1}{2}$ + $\frac{1}{3}$ + $\frac{1}{4}$
= $\frac{6}{12}$ + $\frac{4}{12}$ + $\frac{3}{12}$
=$\frac{13}{12}$
cho mik xin 5* và ctlhn
@ chúc bn hok tốt