Question

the ratio of the length of a field to its width is 5:3 find its length if the width is 42 meters

Answer 1

ratio=5:3
let the length be 5x
breadth =3x
3x=42
X=14
length=5×14=70

Answer 2

let the length be 5x and width be 3x respectively
as given in question width is 42 metres but 
width is 3x 
∴ 3x=42 
x= 42/3 = 14 
if x is 14 then length = 5x
                               = 5×14
                                =70metres