Решение:

a) $$1\frac{4}{9}+2\frac{5}{18} = 1\frac{8}{18}+2\frac{5}{18} = 3\frac{13}{18}$$

б) $$3\frac{5}{24}-1\frac{7}{36} = 3\frac{15}{72}-1\frac{14}{72} = 2\frac{1}{72}$$

B) $$2\frac{7}{30}+3\frac{9}{20}-4\frac{59}{60} = 2\frac{14}{60}+3\frac{27}{60}-4\frac{59}{60} = 5\frac{41}{60}-4\frac{59}{60} = \frac{341}{60} - \frac{299}{60} = \frac{42}{60} = \frac{7}{10}$$

Ответ:

a) $$3\frac{13}{18}$$

б) $$2\frac{1}{72}$$

B) $$\frac{7}{10}$$