计算. 25%x=75 60%x-35%x=125 x-40%x=120 x+15%x=115 15x-30=150 8x+42=178.

问题描述:

计算.
25%x=75
60%x-35%x=125 x-40%x=120
x+15%x=115 15x-30=150 8x+42=178.

(1)25%x=75,
  0.25x÷0.25=75÷0.25,
            x=300;
(2)60%x-35%x=125,
          0.25=125,
   0.25x÷0.25=125÷0.25,
             x=500;
(3)x-40%x=120,
       0.6x=120,
  0.6x÷0.6=120÷0.6,
          x=200;
(4)x+15%x=115,
      1.15x=115,
1.15x÷1.15=115÷1.15,
          x=100;
(5)15x-30=150,
  15x-30+30=150+30,
    15x÷15=180÷15,
          x=12;
(6)8x+42=178,
  8x+42-42=178-42,
     8x÷8=136÷8,
         x=17.