84-54-19=11
789-89-2=698
964-64-59=841
856-256-10=590
-0.5а×(-7в)×(-2с)= -(0.5×7×2)×авс=-7авс
(4/5-3/4)*7,8+(2/3+4/7)*7/13;
1)4/5-3/4=16/20-15/20=1/20=0,05; ///
2)2/3+4/7=14/21+12/21=26/21; ///
3)0,05*7,8=0,39; 1/20*39/5=39/100;///
4)26/21*7/13=2/3; ///
5)39/100+2/3=117/300+200/300=317/300=3 цел17/300
(а-6)*а при а=6
(6-6)*6=0
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