1. Выполните действия: 2 вариант a) 31 16+14 21; 6) 60-13 35-21 45; в) 23 17-9,8 +1818.

a) $$31\frac{16}{21}+14\frac{16}{35}$$ Приведем дробные части к общему знаменателю 105: $$31\frac{16*5}{21*5}+14\frac{16*3}{35*3} = 31\frac{80}{105}+14\frac{48}{105} = (31+14)+\frac{80+48}{105}=45+\frac{128}{105}=45+1\frac{23}{105}=46\frac{23}{105}$$ б) $$60-13\frac{19}{35}-21\frac{27}{45}$$ $$60-13\frac{19}{35}-21\frac{27}{45} = 60-13\frac{19*9}{35*9}-21\frac{27*7}{45*7}=60-13\frac{171}{315}-21\frac{189}{315}=60-(13\frac{171}{315}+21\frac{189}{315})=60-((13+21)+\frac{171+189}{315})=60-(34+\frac{360}{315})=60-(34+1\frac{45}{315})=60-35\frac{45}{315}=59\frac{315}{315}-35\frac{45}{315}=(59-35)+\frac{315-45}{315}=24+\frac{270}{315}=24\frac{270}{315}=24\frac{6}{7}$$ в) $$23\frac{17}{28}-9,8 +18\frac{13}{18} = 23\frac{17}{28} +18\frac{13}{18}-9,8=23\frac{17*9}{28*9}+18\frac{13*14}{18*14}-9,8=23\frac{153}{252}+18\frac{182}{252}-9,8=(23+18)+\frac{153+182}{252}-9,8=41+\frac{335}{252}-9,8=41+1\frac{83}{252}-9,8=(41+1\frac{83}{252})-9,8=42\frac{83}{252}-9,8=42,329-9,8=32,529$$ Ответ: а) $$46\frac{23}{105}$$; б) $$24\frac{6}{7}$$; в) 32,529