д) е) ж)- з)

Решим примеры: д) \(\frac{2}{9} + \frac{1}{12} = \frac{2 \cdot 4}{9 \cdot 4} + \frac{1 \cdot 3}{12 \cdot 3} = \frac{8}{36} + \frac{3}{36} = \frac{8+3}{36} = \frac{11}{36}\) е) \(\frac{7}{24} + \frac{1}{60} = \frac{7 \cdot 5}{24 \cdot 5} + \frac{1 \cdot 2}{60 \cdot 2} = \frac{35}{120} + \frac{2}{120} = \frac{35+2}{120} = \frac{37}{120}\) ж) \(\frac{1}{42} + \frac{2}{63} = \frac{1 \cdot 3}{42 \cdot 3} + \frac{2 \cdot 2}{63 \cdot 2} = \frac{3}{126} + \frac{4}{126} = \frac{3+4}{126} = \frac{7}{126} = \frac{1}{18}\) з) \(\frac{5}{12} + \frac{3}{20} = \frac{5 \cdot 5}{12 \cdot 5} + \frac{3 \cdot 3}{20 \cdot 3} = \frac{25}{60} + \frac{9}{60} = \frac{25+9}{60} = \frac{34}{60} = \frac{17}{30}\)