12.2+(-7 2/5)+(-4 5/6)+(-39 1/2)+50

12+(-7 2/5)+(-4 5/6)+(-39 1/2)+50=10 11/30 1) 12.2+(-7 2/5)=12 2/10-7 2/5=12 1/5-7 2/5=4 4/5 2) 4 4/5+(-4 5/6)=4 20/30-4 24/30=-4/30 3) -4/30+(-39 1/2)=-4/30-39 15/30=-39 19/30 4) -39 19/30+50=10 11/30 Ответ: 10 11/30

[latex]12 \frac{1}{5} -7 \frac{2}{5}-4 \frac{5}{6}-39 \frac{1}{2} +50=11 \frac{6}{5} -7 \frac{2}{5}-4 \frac{5}{6}-39 \frac{1}{2} +50= \\ =4 \frac{4}{5} -4 \frac{5}{6}-39 \frac{1}{2} +50=4 \frac{24}{30} -4 \frac{25}{30}-39 \frac{15}{30} +50= \\ =- \frac{1}{30}- 39 \frac{15}{30} +50= -39 \frac{16}{30} +49 \frac{30}{30} = \\ = 49 \frac{30}{30}-39 \frac{16}{30}=10 \frac{14}{30}=10 \frac{7}{15} [/latex]