l:m =3/2:7/4,m:n=7/3:21/5,l:n=10:21,what is l:m:n

Question

this question is from chapter ratio and proportion.

Answer 1

l:m = 3/2 : 7/4 = 6 : 7

m:n = 7/3 : 21/5 = 35 : 63

l:n = 10 : 21

to do l:m:n we need the letter (m) that's in both l:m and m:n to be the same

l:m = 6 : 7 = 30 : 35

m:n = 35 : 63

so l:m:n = 30 : 35 : 63

does that fit with l:n = 10 : 21 ?

l:n = 10 : 21 = 30 : 63

yes, it fits

Solution:  l:m:n = 30 : 35 : 63