As per question
`6xx` Capital of `A=8xx` capital of `B=10xx` capital of `C=x` (let)
`implies` captal of `A=x/6`
capital of `B=x/8`, and
capital of `C=x/10`
`:.` The ratio of the capitals of A,B and C
`=x/6:x/8:x/10=1/6:1/8:1/10=20:15:12`
Hence the required ratio `=20:15,12`