已知a:b=3:2，b:c=4:5，求a:b:c 已知a/2=b/3=c/4,求a:b:c
\u5df2\u77e5a:b=3:2,b:c=4:5,\u6c42a:b:ca:b=3:2=6:4
b:c=4:5
a:b:c=6:4:5
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a：b=3:2，所以a=(3/2)b，
b：c=4:5，所以c=(5/4)b，
a:b:c=(3/2)b:b:(5/4)b=3/2:1:5/4=6:4:5
b:c=0.5:2/3=>b:c=1/2:2/3,同乘6=>b:c=3:4
a:b=4:5=>a/b=4/5,右边分子分母同乘3=>a/b=12/15
b:c=3:4=>b/c=3/4,右边分子分母同乘5=>b/c=15/20
所以,a:b:c=12:15:20
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