Обчисли:
1) $\frac{3}{8}$ + $\frac{2}{9}$;
2) $\frac{1}{6}$ + $\frac{2}{5}$;
3) $\frac{2}{9}$ + $\frac{11}{15}$;
4) $\frac{7}{12}$ + $\frac{2}{9}$;
5) $\frac{13}{15}$ -$\frac{1}{2}$;
6) $\frac{9}{20}$ - $\frac{13}{30}$;
7) $\frac{11}{16}$ - $\frac{7}{12}$;
8) $\frac{21}{26}$ - $\frac{8}{13}$.
Розв'язок:
1) $\frac{3}{8}$ + $\frac{2}{9}$ = $\frac{27+16}{72}$ = $\frac{43}{72}$;
2) $\frac{1}{6}$ + $\frac{2}{5}$ = $\frac{5+12}{30}$ = $\frac{17}{30}$;
3) $\frac{2}{9}$ + $\frac{11}{15}$ = $\frac{10+33}{45}$ = $\frac{43}{45}$;
4) $\frac{7}{12}$ + $\frac{2}{9}$ = $\frac{21+8}{36}$ = $\frac{29}{36}$;
5) $\frac{13}{15}$ – $\frac{1}{2}$ = $\frac{26–15}{30}$ = $\frac{11}{30}$;
6) $\frac{9}{20}$ – $\frac{13}{30}$ = $\frac{27–26}{60}$ = $\frac{1}{60}$;
7) $\frac{11}{16}$ – $\frac{7}{12}$ = $\frac{33–28}{48}$ = $\frac{5}{48}$;
8) $\frac{21}{26}$ – $\frac{8}{13}$ = $\frac{21–16}{26}$ = $\frac{5}{26}$.