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. |
答
(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.