Question

what should be added to each of the numbers 39,42,9 and 10 to get the numbers which are in proportion?​

Answer 1

Step-by-step explanation:

(39+x):(42+x) = (9+x):(10+x) or

(39+x)(10+x) = (42+x)(9+x), or

390+49x+x^2 = 378+51x+x^2, or

2x = 390–378 = 12.

Or x = 6.

Check: 45/48 = 15/16

(9+6)/(10+6) =15/16. Correct.

So you need to add 6 to each of the 4 numbers : 39, 42, 9 and 10 so that they are in proportion.