What number has to be added to each term of 3 : 5 to make the ratio 5 : 6?

Correct option is D

Given:

Original ratio = 3 : 5

Required: Find the number to be added to each term so that the new ratio becomes 5 : 6

Solution:

Let the number to be added be y.

Then, $$\frac{(3 + y) }{ (5 + y)} =\frac 5 6$$​​

6(3 + y) = 5(5 + y)

18 + 6y = 25 + 5y

6y - 5y = 25 - 18

y = 7

Therefore, the number to be added is 7.