Bài 1:
a, $\frac{2}{3}$ + $\frac{3}{4}$ = $\frac{8}{12}$ + $\frac{9}{12}$ = $\frac{17}{12}$.
b, $\frac{9}{4}$ + $\frac{3}{5}$ = $\frac{45}{20}$ + $\frac{12}{20}$ = $\frac{57}{20}$.
c, $\frac{2}{5}$ + $\frac{4}{7}$ = $\frac{14}{35}$ + $\frac{20}{35}$ = $\frac{34}{35}$
d, $\frac{3}{5}$ + $\frac{4}{3}$ = $\frac{9}{15}$ + $\frac{20}{15}$ = $\frac{29}{15}$.
Chúc bạn học tốt!!!!
