Question

IfA/3=B/4=C/5,thenA:B:C=what​

Answer 1

let,  

a/3 = b/4 = c/5 =k [where k is a constant]  

then,  

a= 3k, b= 4k, c=5k  

now,  

a:b:c= 3k:4k:5k = 3;4;5

Answer 2

given A/3=B/4=C/5

LCM of 3,4,5 is 60

so we can write it as 20A/60=15b/60=12c/60

60 gets canceled so

20A=15b=12c

from this a/b=15/20

                    =3/4

b/c=12/15

     =4/5

so

  A     B      C

   3     4    

           4      5

A:B:C=3:4:5