x:y=3:2 y:z=5:4 x+y+z=66

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x:y=3:2y:z=5:4x+y+z=66x:y=3:2y:z=5:4x+y+z=66x:y=3:2y:z=5:4x+y+z=66x:y=3:2→2x=3y①y:z=5:4→4y=5z②x+y+z=

x:y=3:2 y:z=5:4 x+y+z=66
x:y=3:2 y:z=5:4 x+y+z=66

x:y=3:2 y:z=5:4 x+y+z=66
x:y=3:2→2x=3y ①
y:z=5:4→4y=5z ②
x+y+z=66 ③
①×4+②×3：
8x+12y=12y+15z
8x=15z
x=15z/8
将x=15z/8代入③中：
15z/8+y+z=66
23z/8+y=66 ④
联立②④方程解二元一次方程组得：
y=20
z=16
把y=20代入①中得：
x=30
∴ x=30
y=20
z=16

X=30，Y＝20,Z=15

x:y:z=15:10:8
可以设x=15a
那么y=10a z=8a
15a+10a+8a=66
a=2
x=30 y=20 z=16

x : y = 3 : 2 = (3×5) : (2×5) = 15 : 10
y : z = 5 : 4 = (5×2) : (4×2) = 10 : 8
所以 x : y : z = 15 : 10 : 8
所以设 x = 15k , y = 10k ,z = 8k
因为 x + y + z = 66
所以 15k + 10k + 8k = 66
所以 k = 2
所以
x = 15k = 30
y = 10k = 20
z = 8k = 16

等量代换，设 x = 15k , y = 10k ,z = 8k
15k + 10k + 8k = 66
k = 2
x = 30
y = 20
z = 16

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