Question

31-(12 7/8+3 2/5+6 5/8)-7 4/5
СРОЧНООО ДАМ 30 БАЛЛОВ​

Answer 1

$\displaystyle31-(12\frac{7}{8}+3\frac{2}{5}+6\frac{5}{8})-7\frac{4}{5}=31-((12+3+6)+(\frac{7}{8}+\frac{2}{5}+\frac{5}{8}))-\frac{39}{5}=\\ \\ 31-(21+\frac{19}{10})-\frac{39}{5}=31-(21+1\frac{9}{10})-\frac{39}{5}=31-(21+1+\frac{9}{10})-\frac{39}{5}=\\ \\ 31-(22+\frac{9}{10})-\frac{39}{5}=31-22\frac{9}{10}-\frac{39}{5}=31-\frac{229}{10}-\frac{39}{5}=\frac{3}{10}=0,3$