Tính. 2/15 + 11/15

a) $\frac{2}{15}+\frac{11}{15}=\mathrm{..................}$

c) $\frac{5}{12}+\frac{1}{4}=\mathrm{..................}$

b) $\frac{8}{19}+\frac{7}{19}=\mathrm{..................}$

d) $\frac{7}{20}+\frac{3}{10}=\mathrm{..................}$

a) $\frac{2}{15}+\frac{11}{15}=\frac{2+11}{15}=\frac{13}{15}$

c) $\frac{5}{12}+\frac{1}{4}=\frac{5}{12}+\frac{3}{12}=\frac{8}{12}=\frac{2}{3}$

b) $\frac{8}{19}+\frac{7}{19}=\frac{8+7}{19}=\frac{15}{19}$

d) $\frac{7}{20}+\frac{3}{10}=\frac{7}{20}+\frac{6}{20}=\frac{13}{20}$