д) 2/9 + 1/12= e) 7/24 + 1/60= ж) 1/42 + 2/63= з) 5/12 + 3/20=

д) $$ \frac{2}{9} + \frac{1}{12} = \frac{2 \cdot 4}{9 \cdot 4} + \frac{1 \cdot 3}{12 \cdot 3} = \frac{8}{36} + \frac{3}{36} = \frac{8+3}{36} = \frac{11}{36} $$

Ответ: 11/36

е) $$ \frac{7}{24} + \frac{1}{60} = \frac{7 \cdot 5}{24 \cdot 5} + \frac{1 \cdot 2}{60 \cdot 2} = \frac{35}{120} + \frac{2}{120} = \frac{35+2}{120} = \frac{37}{120} $$

Ответ: 37/120

ж) $$ \frac{1}{42} + \frac{2}{63} = \frac{1 \cdot 3}{42 \cdot 3} + \frac{2 \cdot 2}{63 \cdot 2} = \frac{3}{126} + \frac{4}{126} = \frac{3+4}{126} = \frac{7}{126} = \frac{1}{18} $$

Ответ: 1/18

з) $$ \frac{5}{12} + \frac{3}{20} = \frac{5 \cdot 5}{12 \cdot 5} + \frac{3 \cdot 3}{20 \cdot 3} = \frac{25}{60} + \frac{9}{60} = \frac{25+9}{60} = \frac{34}{60} = \frac{17}{30} $$

Ответ: 17/30