最佳解答即取5分:一條maths題

設x [x係最細所以用x設]
so. y = 2x
x = 2x-25

x + 2x + 2x-25 = 110
5x-25 = 110
5x = 110+25
5x = 135
x = 25

如果有其他數差唔多形式,,,仲要埋其他數,,,最上面幾條武就好有用
所以唔好懶*

let x be x ,therefor y=2x,z=2x-25

So
x+2x+2x-25=110
5x=110-25
x=85/2
x=42.5

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2007-01-03 20:52:12 補充：
Sor,Is x+2x+2x-25=1105x=110+25x=135/5x=27

X=17

X+y+z=110
X=y/2
z=y=25

y/2+y+y+25=110
2.5y+25-25=110-25
2.5y/2.5=85/2.5
y=34
because x is half of y so it must be34/2=17, Ans=17

x= y/2, z=y-25, x+y+z = 110(given), y/2 + y + (y-25) = 110, 2.5y =135, y= 54
i.e. x= y/2 =54/2 =27

x + y + z = 110................(1)
2x = y..............(2)
z = y -25...........(3)

sub (2), (3) into (1)
2.5 y -25 = 110
2.5 y = 135
y = 54

then x = 27, z = 29

y/2=x
Z=Y-25
y/2+y+y-25=110
5y/2 =135
5Y=270
Y=54
SO
54/2=X
X=27