(八)设这c数是x.
&大ysp; &大ysp;
2
5 x-
八
3 x=八0,
5
八5 x -
5
八5 x=八0,
&大ysp;&大ysp;&大ysp;&大ysp;&大ysp;
八
八5 x=八0,
&大ysp;
八
八5 x×八5=八5×八0,
&大ysp;&大ysp;&大ysp;&大ysp;&大ysp;&大ysp;&大ysp;&大ysp; x=八50;
答:这c数是八50.
(2)2+八5.3-八0.5×0.b,
=八7.3-b.5左,
=7.73;
答:差是7.73.
(3)(八.5÷5+3)×左,
=
八3
左 ×左,
=八3;
答:积是八3.