✔ 最佳答案
1. 原價=x , x(1-6%)=$188, x=200...
如果想賺20%, 即係原價 x(1+20%)= 1.2x = $240
2. let x=成本, y=售價
3x=2y, y=(3/2)x, 3/2x100% =(1+50%), 所以盈利百分率= 50%
3. let x= 定價,
x(85%)=x-12,
x - 0.15x = x-12
0.15x=12
x= $80
4. (x+1)/2 = (4-x)/3
3x+3 = 8 - 2x
x = 1
5. x/3 +(x+4)/9 = (2-3x)/12
12x + 4(x+4) = 3(2-3x)
16x +16 = 6 - 9x
25x = -10
x = -0.4 (-2/5)
6. Let x =男生, y=該班學生人數
Step i) x = 3y/5
Step ii) x+(x-9) = y
2x - 9 = y
2(3y/5) - 9 = y
6y - 45 = 5y
y = 45
所以該班學生人數=45
7. let x = 原長度
x(1-15%)(1-40%) = x - 220
x(0.85)(0.4) = x -220
0.34x = x - 220
x = 333.33333333cm
所以繩子原長 333.33333333cm
2007-09-03 09:37:27 補充:
sorry 第七題計錯左"7. let x = 原長度 x(15%)(40%) = 220 x(0.06) =220 x = x - 220x = 366.666666 cm所以繩子原長 366.666666 cm