Question

which number should be subtracted from 12,16 and 21 so that resultant number are in continued proportion​

Answer 1

Suppose 'x' be added to 12,16,21

then , 12+x,16+x,21+x are in continued proportion .

therefore:- 12+x = 16+x

_____ _____

16+x 21+x

(12+x) (21+x) = (61+x) (61+x)

252-256+33x-32x+x^2-x^2=o

-4+x=0

x=4

hope it will help u