Ответ: [tex]7 \frac{4}{21} +2 \frac{1}{6}=7 \frac{8}{42} +2 \frac{7}{42}=9 \frac{15}{42}= 9 \frac{5}{14} \\ \\
3 \frac{5}{36} -1 \frac{19}{45}= 3 \frac{25}{180}-1 \frac{76}{180}=2 \frac{205}{180} — 1\frac{76}{180} =1 \frac{129}{180} =1 \frac{43}{60} [/tex]