1. Вычислить: a) 13/24 - 3/8; б) 13/36 + 7/24; в) 5/6 - 2/3 + 2/9; г) 13/20 - 7/15; д) 11/16 + 5/12; е) 19/30 - 2/5 + 1/3.

Выполним вычисления:

1. 
   

   a) $$\frac{13}{24} - \frac{3}{8} = \frac{13}{24} - \frac{3 \cdot 3}{8 \cdot 3} = \frac{13}{24} - \frac{9}{24} = \frac{13 - 9}{24} = \frac{4}{24} = \frac{1}{6}$$

   
   


2. 
   

   б) $$\frac{13}{36} + \frac{7}{24} = \frac{13 \cdot 2}{36 \cdot 2} + \frac{7 \cdot 3}{24 \cdot 3} = \frac{26}{72} + \frac{21}{72} = \frac{26 + 21}{72} = \frac{47}{72}$$

   
   


3. 
   

   в) $$\frac{5}{6} - \frac{2}{3} + \frac{2}{9} = \frac{5 \cdot 3}{6 \cdot 3} - \frac{2 \cdot 6}{3 \cdot 6} + \frac{2 \cdot 2}{9 \cdot 2} = \frac{15}{18} - \frac{12}{18} + \frac{4}{18} = \frac{15 - 12 + 4}{18} = \frac{7}{18}$$

   
   


4. 
   

   г) $$\frac{13}{20} - \frac{7}{15} = \frac{13 \cdot 3}{20 \cdot 3} - \frac{7 \cdot 4}{15 \cdot 4} = \frac{39}{60} - \frac{28}{60} = \frac{39 - 28}{60} = \frac{11}{60}$$

   
   


5. 
   

   д) $$\frac{11}{16} + \frac{5}{12} = \frac{11 \cdot 3}{16 \cdot 3} + \frac{5 \cdot 4}{12 \cdot 4} = \frac{33}{48} + \frac{20}{48} = \frac{33 + 20}{48} = \frac{53}{48} = 1\frac{5}{48}$$

   
   


6. 
   

   е) $$\frac{19}{30} - \frac{2}{5} + \frac{1}{3} = \frac{19}{30} - \frac{2 \cdot 6}{5 \cdot 6} + \frac{1 \cdot 10}{3 \cdot 10} = \frac{19}{30} - \frac{12}{30} + \frac{10}{30} = \frac{19 - 12 + 10}{30} = \frac{17}{30}$$

   
   

Ответ: а) 1/6; б) 47/72; в) 7/18; г) 11/60; д) 53/48 = 1 5/48; е) 17/30.