Question

已知x:y=3:5，y:z=2:3，求（x+y+z）/(2x-y+z)的值。

Answer 1

x:y=3:5=6:10 y:z=2:3=10:15
所以x:y:z=6:10:15 所以 x/6=y/10=/z/15=t
x=6t y=10t z=15t
（x+y+z）/(2x-y+z) =(6t+10t+15t)/(12t-10t+15t)= 31/17

Answer 2

x:y=3:5，y:z=2:3
x:y:z=6:10:15
设x/6=y/10=z/15=k
∴x=6k, y=10k, z=15k
（x+y+z）/(2x-y+z)
=(6k+10k+15k)/(12k-10k+15k)
=31/17

Answer 3

x:y=3:5，y:z=2:3
x=3/5 y
z=3/2y

（x+y+z）/(2x-y+z)=(3/5y+y+3/2y)/(2*3/5y-y+3/2y)=(31/10y)/(17/10y)=31/17

Answer 4

x:y=3:5，y:z=2:3
设x=6t 则y=10t z=15t
（x+y+z）=31t
(2x-y+z)=17t
（x+y+z）/(2x-y+z)=31/17

Answer 5

已知x:y=3:5，y:z=2:3
则：X=3/5 Y=0.6Y Z= 3/2 Y=1.5Y
（x+y+z）/(2x-y+z) =( 0.6Y+Y+1.5Y)/(1.2Y-y+1.5Y)=31/17

Answer 6

31/17