Bài Làm:
1.
a) $\frac{2}{3}$ + $\frac{5}{3}$ = $\frac{7}{3}$
b) $\frac{6}{5}$ + $\frac{9}{5}$ = $\frac{15}{5}$ = 3
c) $\frac{12}{27}$ + $\frac{7}{27}$ + $\frac{8}{27}$ = $\frac{27}{27}$ = 1
2.
a) $\frac{3}{4}$ + $\frac{2}{7}$ = $\frac{3x7+2x4}{4x7}$ = $\frac{29}{28}$
b) $\frac{5}{16}$ + $\frac{3}{8}$ = $\frac{5}{16}$ + $\frac{6}{16}$ = $\frac{11}{16}$
3.
a) $\frac{3}{15}$ + $\frac{2}{5}$ = $\frac{1}{5}$ + $\frac{2}{5}$
= $\frac{3}{5}$
b) $\frac{4}{6}$ + $\frac{18}{27}$ = $\frac{2}{3}$ + $\frac{2}{3}$
= $\frac{4}{3}$
4.
Đáp số: $\frac{1}{5}$ + $\frac{1}{4}$ + $\frac{3}{10}$ = $\frac{3}{4}$